Short-crested wave dynamic response analysis method and system based on finite volume method

Abstract

The application provides a short-crested wave dynamic response analysis method and system based on a finite volume method, a short-crested wave model is established based on wind wave characteristic parameters under different sea states and ship motion state parameters, a first wave surface equation is calculated under a ground coordinate, a coordinate and frequency conversion method is used to convert the first wave surface equation under the ground coordinate system into a ship body stable coordinate system, a second wave surface equation suitable for the environment around the ship is obtained, a wave-induced pressure model caused by the sea wave is established, a Smith correction term method is used to correct the wave-induced pressure model, and a multi-wave superposition wave-induced pressure model is obtained through a harmonic superposition analysis method; finally, a generalized disturbance force is constructed based on the finite volume method, the dynamic response of the ship in the wind wave can be more accurately predicted, the wave force on the complex ship body can be effectively modeled and simulated, and the calculation precision is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship engineering and ocean engineering, in particular to a short-crested wave dynamic response analysis method and system based on finite volume method. BACKGROUND

[0002] In modern naval warfare, air power has become an indispensable support for naval vessels. With the continuous development and expansion of China's navy in recent years, the demand for shipboard aviation power is also gradually increasing. At the same time, the maturity of shipboard helicopter technology and the continuous development of new vertical take-off and landing aircraft make non-straight deck ships such as frigates and destroyers play an increasingly important role in the delivery of shipboard aviation power.

[0003] However, the marine environment mainly affected by wind and wave and the marine environment mainly affected by the wake flow and deck disturbance will directly affect the flight performance of shipboard helicopters and other aircraft, and even directly endanger the safety of flight. Especially in high sea conditions, due to the severe rolling of the ship body and the harsh flow field environment, shipboard helicopters and other aircraft often have difficulty in normally performing take-off and landing tasks, which poses a severe challenge to the shipboard aviation combat capability.

[0004] The existing technology has certain limitations in dealing with these problems. For example, the existing interference force and interference torque calculation method uses a square ship assumption, that is, the ship body is approximated as a rectangular box. However, in actual engineering, the ship body will have a complex shape, and obviously the above method will cause distortion of the simulation and the calculation result is not accurate enough.

[0005] Therefore, there is an urgent need for a method that can effectively model and simulate the interference force and torque on a complex ship body to improve the safety and efficiency of shipboard aviation operations. SUMMARY

[0006] The present application provides a short-crested wave dynamic response analysis method based on finite volume method to solve the problems of inaccurate calculation results and simulation distortion in the calculation process of the interference force and torque on a complex ship body. The method establishes a short-crested wave model based on the characteristic parameters of wind waves and the motion state parameters of the ship, uses a specific calculation method and coordinate transformation method to obtain the wave surface equation, and uses a specific correction method to obtain the multi-wave superposition wave pressure model. Based on the finite volume method, a generalized interference force (dynamic response) is constructed, which can more accurately predict the dynamic response of the ship in wind waves and effectively model and simulate the wave force on a complex ship body, effectively improving the calculation accuracy. The present application also relates to a short-crested wave dynamic response analysis system based on finite volume method.

[0007] The technical scheme of the present application is as follows:

[0008] A short-crested wave dynamic response analysis method based on the finite volume method, characterized in that it comprises the following steps:

[0009] Parameter acquisition and coordinate system establishment step: acquire wind wave characteristic parameters under different sea states and ship motion state parameters, and establish a ground coordinate system with an arbitrary point on the sea level as the origin, the ship movement direction as the longitudinal axis, the right side of the ship parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establish a ship body stable coordinate system with the ship center of mass as the origin, the ship movement direction as the longitudinal axis, the right side of the ship parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establish a ship body coordinate system with the ship center of mass as the origin, the direction of the ship bow as the longitudinal axis, the direction of the right side of the ship as the transverse axis, and the direction of the bottom of the ship as the vertical axis; the wind wave characteristic parameters include wave amplitude, wave number, main propagation direction of wind wave, propagation direction of wind wave harmonic, wind wave angular frequency, wind wave mode transformation time, wind wave inherent period, and wind wave inherent wave speed; the ship motion state parameters include ship speed, encounter period, and encounter angular frequency;

[0010] Short-crested wave model construction step: in the ground coordinate system, based on the wave amplitude, wave number, main propagation direction of wind wave, propagation direction of wind wave harmonic, and wind wave mode transformation time, establish a plane wave equation about the wave height, and recursively obtain the short-crested wave model according to the plane wave equation;

[0011] The wave surface equation and the sea wave height calculation steps are as follows: the direction spectrum of the short-crested wave is calculated according to the propagation direction of the wind wave, and a first expression about the long-crested wave energy is constructed according to the wave amplitude and the seawater density on the ground coordinate; the angular frequency interval is established according to the wind wave angular frequency and the frequency band width set based on the wind wave angular frequency, and then a second expression about the long-crested wave energy in the angular frequency interval is obtained; a third expression about the long-crested wave energy spectrum is obtained by recursively deriving the second expression, and the long-crested wave energy spectrum is calculated; the short-crested wave spectrum is calculated according to the direction spectrum of the short-crested wave and the long-crested wave energy spectrum, and a fourth expression about the short-crested wave energy is established based on the short-crested wave spectrum; a first wave surface equation of the short-crested wave is calculated from the fourth expression and the short-crested wave model; then a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship speed direction and the wind wave main propagation direction is taken as the ship encounter angle; a second relationship about the encounter period is established based on the ship encounter angle, the wind wave inherent period, the wind wave inherent wave speed and the ship speed; a third relationship about the encounter angular frequency is established based on the ship encounter angle, the wind wave angular frequency, the wind wave inherent wave speed and the ship speed; the first wave surface equation in the ground coordinate system is converted into the ship body stable coordinate system by using the coordinate and frequency conversion method based on the first relationship, the second relationship and the third relationship, and a second wave surface equation suitable for the ship surrounding environment is obtained, and the sea wave height encountered by the ship during the navigation process is calculated according to the second wave surface equation.

[0012] The multi-wave superposition wave pressure model obtaining step is as follows: the depth of the sea surface from the free surface of a certain point under water is calculated according to the water surface depth under the static water condition and the sea wave height encountered by the ship during the navigation process in the ship body stable coordinate system, and a fifth expression about the pressure of the certain point under water is constructed according to the sea surface depth and the atmospheric pressure; a sixth expression about the pressure of the certain point under water in the short-crested wave condition is calculated according to the fifth expression and the short-crested wave model; the wave pressure model caused by the sea wave is obtained according to the sixth expression, and the wave pressure model is modified by using the Smith correction term method to obtain the modified wave pressure model; and the modified wave pressure model is expressed as the superposition of multiple cosine waves by using the harmonic superposition analysis method, and the multi-wave superposition wave pressure model is obtained.

[0013] The generalized wave disturbance force construction step is: in the ship body stable coordinate system, the ship is divided into a plurality of triangular face elements based on the finite volume method, a vector from the ship mass center to the center of a triangular face element is taken as a vector of the triangular face element, the wave fluctuation pressure of the triangular face element is calculated according to the multi-wave superposition wave fluctuation pressure model, the wave force of the triangular face element is calculated according to the area, normal vector and wave fluctuation pressure of the triangular face element, and the wave moment of the triangular face element is calculated according to the vector and the calculated wave force of the triangular face element; the wave force and the wave moment of the whole ship are calculated based on the wave force and the wave moment of all the triangular face elements; the wave force and the wave moment of the whole ship in the ship body stable coordinate system are converted into the ship body coordinate system by using the coordinate and frequency conversion method, the component array of the wave force of the whole ship and the component array of the wave moment of the whole ship are obtained, and the generalized wave disturbance force is constructed to realize the short-crested wave dynamic response analysis.

[0014] Preferably, in the wave surface equation and sea wave height calculation step, when the frequency band width in the third expression tends to zero, the integral expression of the long-crested wave energy is calculated according to the first expression and the third expression, and the relationship between the sea wave harmonic amplitude and the spectral density function is calculated according to the integral expression.

[0015] Preferably, in the parameter acquisition and coordinate system establishment step, the wind wave characteristic parameters further include a wavelength, and the wave number is calculated according to the wavelength.

[0016] Preferably, the coordinate and frequency conversion method includes coordinate conversion based on a rotation matrix and conversion of wave frequency to encounter frequency.

[0017] A short-crested wave dynamic response analysis system based on the finite volume method, characterized by comprising a parameter acquisition and coordinate system establishment module, a short-crested wave model construction module, a wave surface equation and sea wave height calculation module, a multi-wave superposition wave fluctuation pressure model acquisition module and a generalized wave disturbance force calculation module connected in sequence,

[0018] The parameter acquisition and coordinate system establishment module acquires wind wave characteristic parameters under different sea states and ship motion state parameters, and establishes a ground coordinate system with any point on the sea level as an origin, a ship motion direction as a longitudinal axis, a right side of the ship and a direction parallel to the sea level as a transverse axis, and the earth center as a vertical axis; establishes a ship body stable coordinate system with a ship center of mass as an origin, a ship motion direction as a longitudinal axis, a right side of the ship and a direction parallel to the sea level as a transverse axis, and the earth center as a vertical axis; and establishes a ship body coordinate system with a ship center of mass as an origin, a ship bow direction as a longitudinal axis, a right side of the ship as a transverse axis, and a ship bottom direction as a vertical axis; the wind wave characteristic parameters include a wave amplitude, a wave number, a main propagation direction of the wind wave, a propagation direction of a wind wave harmonic, a wind wave angular frequency, a wind wave form transformation time, a wind wave inherent period, and a wind wave inherent wave speed; and the ship motion state parameters include a ship speed, an encounter period, and an encounter angular frequency;

[0019] The short-crested wave model construction module establishes a wave equation about a sea wave height based on the wave amplitude, the wave number, the main propagation direction of the wind wave, the propagation direction of the wind wave harmonic, and the wind wave form transformation time in the ground coordinate system, and recursively obtains the short-crested wave model according to the wave equation;

[0020] The wave surface equation and sea wave height calculation module calculates a short-crested sea wave direction spectrum according to the propagation direction of the wind wave harmonic, and constructs a first expression about long-crested sea wave energy according to the wave amplitude and sea water density in the ground coordinate system, establishes an angular frequency interval according to the wind wave angular frequency and a frequency band width set based on the wind wave angular frequency, and further obtains a second expression about long-crested sea wave energy in the angular frequency interval, recursively obtains a third expression about the long-crested wave energy spectrum from the second expression, and further calculates the long-crested wave energy spectrum; calculates a short-crested wave spectrum according to the short-crested sea wave direction spectrum and the long-crested wave energy spectrum, establishes a fourth expression about short-crested sea wave energy based on the short-crested wave spectrum, and calculates a first wave surface equation of the short-crested wave from the fourth expression and the short-crested wave model; then establishes a first relationship between the encounter period and the encounter angular frequency, and takes an angle between a ship speed direction and the main propagation direction of the wind wave as a ship encounter angle, establishes a second relationship about the encounter period based on the ship encounter angle, the wind wave inherent period, the wind wave inherent wave speed, and the ship speed, and establishes a third relationship about the encounter angular frequency based on the ship encounter angle, the wind wave angular frequency, the wind wave inherent wave speed, and the ship speed; based on the first relationship, the second relationship, and the third relationship, and by using a coordinate and frequency transformation method, the first wave surface equation located in the ground coordinate system is converted into the ship body stable coordinate system to obtain a second wave surface equation suitable for the environment around the ship, and the sea wave height encountered by the ship during the navigation process is calculated according to the second wave surface equation;

[0021] The multi-wave superposition fluctuation pressure model acquisition module, under the ship body stable coordinate system, calculates the depth of a certain point under water from the free liquid surface according to the liquid depth under the static water condition and the wave height encountered by the ship in the sailing process, and constructs a fifth expression about the pressure of the certain point under water according to the depth of the sea surface and the atmospheric pressure; calculates a sixth expression of the pressure of the certain point under water in the short-crested wave condition according to the fifth expression and the short-crested wave model; obtains the fluctuation pressure model caused by the wave according to the sixth expression, and modifies the fluctuation pressure model by using the Smith correction term method to obtain the modified fluctuation pressure model; and represents the modified fluctuation pressure model as the superposition of a plurality of cosine waves by using the harmonic superposition analysis method to obtain the multi-wave superposition fluctuation pressure model.

[0022] The generalized wave disturbance force calculation module, under the ship body stable coordinate system, divides the ship into a plurality of triangular face elements based on the finite volume method, and takes the vector from the ship mass center to the center of a certain triangular face element as the vector of the triangular face element, calculates the fluctuation pressure of the triangular face element according to the multi-wave superposition fluctuation pressure model, calculates the wave force of the triangular face element according to the area, normal vector and fluctuation pressure of the triangular face element, and calculates the wave moment of the triangular face element according to the vector and the calculated wave force of the triangular face element; calculates the wave force and the wave moment of the whole ship based on the wave force and the wave moment of all the triangular face elements; and converts the wave force and the wave moment of the whole ship in the ship body stable coordinate system into the ship body coordinate system by using the coordinate and frequency conversion method to obtain the component array of the wave force of the whole ship and the component array of the wave moment of the whole ship, and further construct the generalized wave disturbance force to realize the short-crested wave dynamic response analysis.

[0023] Preferably, in the wave surface equation and wave height calculation module, when the frequency band width in the third expression tends to zero, the integral expression of the long-crested wave energy is calculated according to the first expression and the third expression, and the relationship between the wave harmonic amplitude and the spectral density function is calculated according to the integral expression.

[0024] Preferably, in the parameter acquisition and coordinate system establishment module, the wave length is calculated according to the wave length to obtain the wave number.

[0025] Preferably, the coordinate and frequency conversion method includes the coordinate conversion based on the rotation matrix and the conversion of the wave frequency to the encounter frequency.

[0026] The present application has the following beneficial effects:

[0027] The application provides a short-crested wave dynamic response analysis method based on a finite volume method, which is based on wind wave characteristic parameters under different sea conditions and ship motion state parameters, and can more accurately and quickly describe the behavior of wind waves and the influence of wind waves on ships by establishing a short-crested wave model containing wave amplitude, wave number, main propagation direction of wind waves, propagation direction of wind wave harmonics and various characteristic parameters, thereby improving the accuracy of the model; and based on the established ground coordinate system and ship body stable coordinate system, the wind wave model is converted from the ground coordinate system to the ship body coordinate system through a coordinate and frequency conversion method, so that the actual motion state of the ship in the sea waves can be more accurately reflected; then a second wave surface equation suitable for the environment around the ship is calculated by using a specific calculation method and constructed expressions and relationships, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation, so that the actual sea wave situation can be more accurately reflected, especially for accurate wave height prediction under complex sea conditions, thereby reducing the risk of the ship encountering extreme sea conditions, and protecting the safety of the ship and its passengers; then the wave pressure model obtained by the established expressions is modified by using the Smith correction term method to obtain a modified wave pressure model, so as to improve the calculation accuracy and effectively and accurately evaluate the stress condition of the ship in the wind waves; and a multi-wave superposition wave pressure model is obtained by a harmonic superposition analysis method, the multi-wave superposition wave pressure model considers the pressure change of a certain point under water, considers the interaction and nonlinear effect between wind waves, effectively improves the accuracy and reliability of wave pressure calculation, and makes the prediction of the dynamic response of the ship more accurate; finally, a generalized wave disturbance force is constructed based on the finite volume method and by using a specific calculation method, so that the dynamic response of the ship in the wind waves can be more accurately predicted, the wave force on the complex ship body can be effectively modeled and simulated, the calculation accuracy is effectively improved, the take-off and landing safety of the ship-borne helicopter under high sea conditions can be more accurately evaluated, and it is of great significance to ensure the safe take-off and landing of the ship-borne helicopter under high sea conditions. The application can effectively improve the take-off and landing ability and safety of the ship-borne aircraft under complex sea conditions, thereby enhancing the overall combat effectiveness of the ship-borne aviation power.

[0028] The application also relates to a short-crested wave dynamic response analysis system based on the finite volume method, which corresponds to the short-crested wave dynamic response analysis method based on the finite volume method, and can be understood as a system for realizing the short-crested wave dynamic response analysis method based on the finite volume method, and comprises a parameter acquisition and coordinate system establishment module, a long-crested wave model construction module, a wave surface equation and wave height calculation module, a multi-wave superposition wave fluctuation pressure model acquisition module and a generalized wave disturbance force construction module which are connected in sequence, each module is mutually coordinated, a short-crested wave model is established based on characteristic parameters of wind waves and motion state parameters of a ship, a wave surface equation is obtained by using a specific calculation method and a coordinate conversion method, a multi-wave superposition wave fluctuation pressure model is obtained by using a specific correction method, and then a generalized wave disturbance force is constructed based on the finite volume method and by using a specific calculation method, so that the dynamic response of the ship in wind waves can be more accurately predicted, the wave force on a complex ship body can be effectively modeled and simulated, and the calculation precision is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a flow chart of the ship dynamic stability modeling method based on multi-external force coupling of the application.

[0030] Figure 2 is a ground coordinate system schematic diagram.

[0031] Figure 3 is a ship body stability coordinate system schematic diagram.

[0032] Figure 4 is a ship body coordinate system schematic diagram.

[0033] Figure 5 is a ship body stability coordinate system and ship body coordinate system conversion relationship schematic diagram.

[0034] Figure 6 is a plane wave waveform schematic diagram.

[0035] Figure 7 is a ship sailing in wind waves schematic diagram.

[0036] Figure 8 is a ship sailing in wind waves schematic diagram. DETAILED DESCRIPTION

[0037] The application will be described below in combination with the drawings.

[0038] The application relates to a short-crested wave dynamic response analysis method based on the finite volume method, and a flow chart of the method is shown in Figure 1 The method comprises the following steps in sequence:

[0039] Parameter acquisition and coordinate system establishment steps: obtain wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the longitudinal axis, the direction of the ship's starboard side and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establish a hull stable coordinate system with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the direction of the ship's starboard side and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establish a hull coordinate system with the ship's center of mass as the origin, the direction of the ship's bow as the longitudinal axis, the direction of the ship's starboard side as the transverse axis, and the direction of the ship's bottom as the vertical axis; the wind and wave characteristic parameters include amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave shape transformation, wind and wave natural period, and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency.

[0040] Specifically, the ground coordinate system E-ξηζ is as follows Figure 2 As shown in Figure 1, it is a fixed inertial coordinate system fixed to the earth, used to describe the motion state of ocean waves. The origin of the coordinate system E can be any point on the sea level, the center of the earth is the vertical axis, that is, the Eζ axis points to the center of the earth, the direction of the ship's motion is the longitudinal axis, that is, the Eξ axis points to the direction of the ship's motion, the direction to the starboard side of the ship and parallel to the sea level is the transverse axis, that is, the Eη axis points to the starboard side of the ship and parallel to the sea level, the Eξ axis and the Eη axis are located in the sea level and are perpendicular to each other, and the distribution of the three coordinate axes conforms to the right-hand rule. The hull stable coordinate system Ox s y s z s like Figure 3 As shown in Figure 1, it is a coordinate system that moves with the ship and is used to describe the motion of the ship hull in a stable state. The origin of the coordinate system O is the center of mass of the ship, and the direction of the ship's motion is the longitudinal axis, that is, Ox s The axis points to the direction of the ship's movement, and the direction to the starboard side of the ship and parallel to the sea level is the transverse axis, that is, Oy s Pointing to the starboard side of the ship and parallel to the sea level, with the center of the earth as the vertical axis, that is, Oz s The axis points to the center of the earth, Ox s y s The plane is parallel to the sea level, and the distribution of the three coordinate axes conforms to the right-hand rule. b y b z b ,like Figure 4 As shown, it is a motion coordinate system fixed to the hull, used to describe the motion state of the ship hull. The origin of the coordinate system O is the center of mass of the ship, and the direction of the bow of the ship is the longitudinal axis, that is, Ox b The axis coincides with the ship's roll axis and points to the bow, and the direction of the starboard side of the ship is the transverse axis, that is, Oy bThe axis coincides with the ship's pitch axis and points to the starboard side of the ship, and the direction of the ship's bottom is the vertical axis, i.e., Oz b The axis coincides with the ship's pitch axis and points to the starboard side of the ship, and the direction of the ship's bottom is the vertical axis, i.e., Oz

[0041] Table 1

[0042]

[0043] The three translational position variables are surge x, sway y, and heave (or sink) z. The three translational position variables are surge x, sway y, and heave (or sink) z. The body coordinate system can be obtained by three simple rotations of the body-fixed coordinate system, as shown in Figure 5 The three rotations are: rotating the bow yaw angle ψ around the z s axis to obtain O-x1y1z1 s ; rotating the pitch angle θ around the y1 axis to obtain O-x1y1z2 b ; and rotating the roll angle φ around the x b axis to obtain O-x2y2z3 . b b b .

[0044] The short-crested wave model construction steps: based on the wave amplitude, wave number, the main propagation direction of the wind wave, the propagation direction of the wind wave harmonic, and the time of the wind wave form transformation, the plane wave equation about the wave height is established, and the short-crested wave model is obtained by recursion according to the plane wave equation.

[0045] During the process of ship sailing in high sea conditions, it will be disturbed by various marine environments such as sea waves, sea winds, sea currents and so on, among which random sea waves are the most important disturbance factor. Therefore, it is necessary to master the distribution of random sea waves under high sea conditions before analyzing the motion state of the ship under high sea conditions. Specifically, sea wave simulation has always been a very complex problem. In the real situation, the wind wave on the sea surface is extremely complex irregular random three-dimensional wave, so it is very difficult to accurately model the sea wave. However, in the process of studying the ship motion problem, it is considered that the wind wave is generally unidirectional along the wind direction, that is, the wind wave only propagates along its main propagation direction (i.e., the ξ axis of the ground coordinate system), so it can be assumed that the wave crest and trough of the sea wave are parallel to each other and perpendicular to the propagation direction of the sea wave. At this time, the main propagation direction of the wind wave is the ξ axis, and the wave height (the height of the wave surface) ζ of a certain point on the sea surface is represented as a two-variable function of ξ and time t, that is, ζ = ζ(ξ, t). According to the Longuet-Higgins model, the long-crested wave model of irregular wind waves can be regarded as the superposition of a large number of plane waves with different wave amplitudes (amplitudes), wavelengths, and initial phases in the vertical plane of the main propagation direction of the wind wave. According to the following fluid mechanics assumptions:​​

[0046] a) fluid is incompressible;

[0047] b) fluid has only potential velocity;

[0048] c) wind wave is small amplitude.

[0049] The plane progressive wave propagating along the ξ axis can be expressed as:

[0050] ζ = ζ a cos(kξ-ωt) (1)

[0051] wherein, ξ is the wave height of wind wave (also can be called as the distance of wave surface deviating from sea level, or the height of wave surface relative to mean sea level); ζ a is the wave amplitude; k is the wave number; λ is the wave length, the wave number and the wave length have the relationship: k = 2π / λ; ω is the angular frequency of wind wave. t is the time of wind wave angular frequency and wind wave form transformation, describing the change of wind wave with time, when t = 0, the plane progressive wave shape is as shown in the following figure. Figure 6

[0052] According to the plane progressive wave formula, the long-crested wave model (also can be called as Longuet-Higgins model of long-crested wave) can be derived as follows:

[0053]

[0054] wherein, k i , ω i , ζ ai are the wave number, angular frequency and wave amplitude of the i-th harmonic respectively; ε i is the random initial phase of the i-th harmonic between 0 and 2π.

[0055] However, the above long-crested wave model still has problems of being unable to accurately capture the propagation characteristics of wind wave and slow operation speed, because it only considers the main propagation direction of wind wave as the ξ axis. Therefore, the short-crested wave model of wind wave is introduced, which considers that the propagation directions of different harmonics of wind wave will propagate along different propagation angles μ, and the angle μ is positive when the right-hand rule is positively rotated around the ζ axis when propagating along the ξ axis. Therefore, in the short-crested wave model of wind wave, the wave height ζ of wind wave at a certain point on the sea surface should be expressed as a three-variable function ζ = ζ(ξ, η, t), and the plane progressive wave equation propagating along the propagation angle μ is described again in the three-dimensional ground coordinate system E-ξηζ as follows:

[0056] ζ = ζ a cos[k(ξcosμ j -ηsinμ j )-ωt] (3)

[0057] ​where ζ a is the wave amplitude, k is the wave number, ζ is the wave height, μ represents the propagation angle, different harmonics of wind waves propagate along different propagation angles μ, the main propagation direction of wind waves along the ξ axis, the main propagation direction of wind waves along the η axis, and ω is the angular frequency of wind waves.

[0058] The short-crested wave model (also known as the Longuet-Higgins model of short-crested wave) derived from the wave equation according to the plane is as follows:

[0059]

[0060] The short-crested wave model takes into account the main propagation direction of wind waves along the ξ axis and the η axis, and introduces the propagation direction of wind wave harmonics as propagating along different propagation angles μ, so that the short-crested wave model can more accurately capture the propagation characteristics of sea waves (including the propagation direction and energy distribution of wind waves). And because the short-crested wave model contains more degrees of freedom, it can more meticulously depict the irregularity of sea waves, thereby improving the accuracy of the prediction, which is crucial for studying sea wave dynamics, ocean engineering design and safety assessment. At the same time, the short-crested wave model is also applicable to various complex marine environments, including sea wave conditions under different sea areas, seasons and weather conditions, and can better simulate the behavior of real-world wind waves, providing a more reliable basis for scientific research and engineering practice in related fields.

[0061] The wave surface equation and the sea wave height calculation steps are as follows: the direction spectrum of the short-crested wave is calculated according to the propagation direction of the wind wave harmonic, and a first expression about the long-crested wave energy is constructed according to the wave amplitude and the seawater density under the ground coordinate; an angular frequency interval is established according to the wind wave angular frequency and the frequency band width set based on the wind wave angular frequency, and a second expression about the long-crested wave energy in the angular frequency interval is obtained; a third expression about the long-crested wave energy spectrum is obtained by recursively deriving the second expression; and the long-crested wave energy spectrum is calculated; the short-crested wave spectrum is calculated according to the direction spectrum of the short-crested wave and the long-crested wave energy spectrum, and a fourth expression about the short-crested wave energy is established based on the short-crested wave spectrum; a first wave surface equation of the short-crested wave is calculated from the fourth expression and the short-crested wave model; then a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship speed direction and the wind wave main propagation direction is taken as the ship encounter angle; a second relationship about the encounter period is established based on the ship encounter angle, the wind wave inherent period, the wind wave inherent wave speed and the ship speed; a third relationship about the encounter angular frequency is established based on the ship encounter angle, the wind wave angular frequency, the wind wave inherent wave speed and the ship speed; the first wave surface equation located in the ground coordinate system is converted into the ship body stable coordinate system by using the coordinate and frequency conversion method based on the first relationship, the second relationship and the third relationship, and a second wave surface equation suitable for the environment around the ship is obtained; and the sea wave height encountered by the ship during the navigation process is calculated according to the second wave surface equation.

[0062] Specifically, first, the direction spectrum of the short-crested wave is calculated according to the propagation direction of the wind wave harmonic, and the calculation is performed according to the following formula:

[0063]

[0064] The 12th ITTC recommends that n in M(μ) is temporarily taken as 1, and then:

[0065]

[0066] Then, according to the knowledge of fluid mechanics, the long-crested wave has energy, so a first expression about the long-crested wave energy E is constructed according to the wave amplitude and the seawater density under the ground coordinate, and is expressed according to the following formula:

[0067]

[0068] Wherein, i is the harmonic number, ζ ai is the wave amplitude of the i-th harmonic, ρ is the seawater density, and g is the gravitational acceleration.

[0069] An angular frequency interval (ω, ω+dω) is established according to the wind wave angular frequency ω and the frequency band width dω set based on the wind wave angular frequency, and a second expression about the long-crested wave energy in the angular frequency interval is obtained, and is expressed according to the following formula:

[0070]

[0071] A third expression for the long-crested wave energy spectrum S ζ (ω) is given by:

[0072]

[0073] The long-crested wave energy spectrum S ζ (ω) can be calculated according to equation 9.

[0074] Preferably, when the frequency band width tends to zero in the third expression, i.e. dω→0, the integral expression for the long-crested wave energy is calculated according to the first expression and the third expression, and is given by:

[0075]

[0076] According to the integral expression for the long-crested wave energy, the wave harmonic amplitude ζ ai is obtained, which is related to the spectral density function S ζ (ω) as follows:

[0077]

[0078] The short-crested wave spectrum is obtained by adding the directional spectrum M(μ) of the short-crested wave to the long-crested wave energy spectrum S ζ (ω), and thus the short-crested wave spectrum is calculated according to the directional spectrum of the short-crested wave and the long-crested wave energy spectrum, and is given by:

[0079] S ζ (ω,μ) = S ζ (ω)M(μ) (10)

[0080] A fourth expression for the short-crested wave energy is established based on the short-crested wave spectrum, and is given by:

[0081]

[0082] The first wave surface equation of the short-crested wave is obtained by discretizing the above equation 11 and substituting into the short-crested wave model, and is given by:

[0083]

[0084] In summary, the state of the sea wave at a certain time (the state includes the wave height, energy distribution, wave shape, and phase distribution of the sea wave) can be obtained.

[0085] When a ship is sailing on the sea, due to its certain speed, the frequency of the waves it encounters is different from the frequency of the waves at a fixed point on the sea. When the ship is sailing against the waves, the frequency of the waves it encounters is higher than the frequency of the waves at a fixed point on the sea; on the contrary, when the ship is sailing with the waves, the frequency of the waves it encounters is lower than the frequency of the waves at a fixed point on the sea. Therefore, when studying the problem of ships sailing in wind and waves, we first define the wave period encountered by the ship as the encounter period T e , the corresponding angular frequency is called the encounter angular frequency ω e , which is related to the encounter period, and the first relationship between the encounter period and the encounter angular frequency is established, that is, In addition, if Figure 7 As shown, the encounter period of the ship is T e and the encounter angular frequency ω e The natural period of the sea wave T, the angular frequency of the wind and wave ω (also called the natural angular frequency ω), the ship speed V, and the ship encounter angle μ e (the angle between the ship speed V and the wind and wave propagation direction) and the inherent wave speed C of the wind and waves are related, and the relationship can be expressed as:

[0086]

[0087]

[0088] According to the above equations (13), (14) and the encounter period T e and the encounter angular frequency ω e The geometric relationship of the wave surface is obtained, and the first wave surface equation in the ground coordinate system, that is, Equation (12), is transformed into the hull stable coordinate system through the coordinate and frequency transformation method (coordinate transformation based on the rotation matrix and transformation from wave frequency to encounter frequency). The second wave surface equation applicable to the short-peak wave and wind wave environment around the ship is obtained, which is expressed as follows:

[0089]

[0090] According to the second wave surface equation of short-peaked wind waves, that is, according to formula (15), the wave height ζ encountered by the ship during navigation can be calculated: e , which indicates the shape of the wave surface encountered by the ship during navigation.

[0091] Steps for obtaining a multi-wave superposition fluctuation pressure model: in the hull stable coordinate system, calculate the sea surface depth of a certain underwater point from the free liquid surface according to the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation, and construct a fifth expression for the pressure at a certain underwater point according to the sea surface depth and atmospheric pressure; calculate a sixth expression for the pressure at a certain underwater point under short-peak wave conditions according to the fifth expression and the short-peak wave wind and wave model; obtain a fluctuation pressure model caused by waves according to the sixth expression, and use the Smith correction term method to correct the fluctuation pressure model to obtain a corrected fluctuation pressure model; and express the corrected fluctuation pressure model as the superposition of multiple cosine waves through the harmonic superposition analysis method to obtain a multi-wave superposition fluctuation pressure model.

[0092] Specifically, this step can also be understood as studying the distribution of the subsurface seawater pressure field. During this research, it is generally believed that the interference forces and moments exerted by waves on the hull are caused by fluctuations in the subsurface pressure field distribution. Therefore, before analyzing the wind and wave forces and moments acting on the ship, the distribution of the subsurface seawater pressure field must first be studied. Based on the basic water pressure formula, the fifth expression, or the pressure P at a specific point underwater, can be expressed as:

[0093] P=P0+ρgh (16)

[0094] Where P0 is the atmospheric pressure; ρ is the density of seawater; g is the acceleration due to gravity; and h is the depth of a point underwater (also called a research point) from the free surface. Under wave conditions, the sea surface depth h can be expressed as the liquid surface depth z under still water conditions and the wave height ζ encountered by the ship during navigation. e The sum is expressed as follows:

[0095] h=z+ζ e (17)

[0096] According to the fifth expression and the short-peak wave wind wave model, the sixth expression of the pressure at a certain point underwater under the condition of short-peak wave waves is calculated. That is, the sixth expression of the pressure at a certain point underwater under the condition of long-peak wave waves is obtained by substituting equation (4) into equation (16), as shown below:

[0097] P=P0+ρgz+ρgζ a cos(kξ-ωt) (18)

[0098] Based on the sixth expression, the pressure fluctuation model caused by the waves is defined as ΔP, then:

[0099] ΔP=ρgζ a cos(kξ-ωt) (19)

[0100] According to the Smith effect, the wave surface fluctuation amplitude is affected by the depth, so the Smith correction term is used to modify the fluctuating pressure model, and the modified fluctuating pressure model is obtained, as shown in the following formula:

[0101]

[0102]

[0103] ΔP=e -kz ρgζ a cos(kξ-ωt) (22)

[0104] In the ship body stable coordinate system, there are:

[0105] ΔP=e -kz ρgζ a cos(kx s cosμ e +ky s sinμ e -ωe t ) (23)

[0106] The modified fluctuating pressure model is expressed as a superposition of multiple cosine waves by the harmonic superposition analysis method, and the multi-wave superposition fluctuating pressure model is obtained, that is, formula (23) is expressed in the form of cosine wave superposition, as shown in the following formula:

[0107]

[0108] The generalized wave disturbance force construction step can also be understood as a ship disturbance force and moment analysis step. By dividing the complex ship body into a surface grid (triangular surface element), the wave force on each triangular surface element is solved and superimposed, and finally the wave force on the complex ship body can be effectively modeled and simulated. In the ship body stable coordinate system, the ship is divided into multiple triangular surface elements based on the finite volume method, and the vector from the ship mass center to the center of a triangular surface element is taken as the vector of the triangular surface element. The wave fluctuating pressure on the triangular surface element is calculated according to the multi-wave superposition fluctuating pressure model, and the wave force on the triangular surface element is calculated according to the area, normal vector and wave fluctuating pressure of the triangular surface element. The wave moment on the triangular surface element is calculated according to the vector and the calculated wave force. Based on the wave force and wave moment of all triangular surface elements, the overall wave force and wave moment of the ship are calculated. The overall wave force and wave moment of the ship in the ship body stable coordinate system are converted into the ship body coordinate system by using the coordinate and frequency transformation method, and the component array of the overall wave force and the component array of the overall wave moment are obtained, and the generalized wave disturbance force is constructed.

[0109] Specifically, asFigure 8 As shown, in the ship body stability coordinate system, the ship is divided into N triangular face elements based on the finite volume method, and the vector from the ship mass center O to the center of the i-th triangular face element is defined as the vector radius r i of the triangular face element. Then the wave pressure and wave force at the center of each face element can be calculated by the multi-wave superposition wave pressure model, wherein the wave pressure ΔP i experienced by the triangular face element is calculated according to the multi-wave superposition wave pressure model. The wave force experienced by the i-th triangular face element is calculated according to the area, normal vector and wave pressure of the triangular face element, and is calculated according to the following formula:

[0110] ΔF i = ΔP i n i S i (25)

[0111] In the above formula, subscript i represents the i-th triangular face element; n i is the normal vector of the i-th triangular face element; S i is the area of the i-th face element; ΔP i is the wave pressure ΔP i experienced by the i-th triangular face element, which is a four-parameter function ΔP(x s , y s , z, t) composed of x s , y s , z and t, wherein x s , y s , z can be directly obtained from the face mesh file of the ship.

[0112] The above vector from the ship mass center O to the center of the i-th triangular face element is defined as the vector radius r i of the triangular face element. Then the wave moment experienced by the i-th triangular face element can be calculated according to the vector radius of the i-th triangular face element and the calculated wave force ΔF i , and is calculated according to the following formula:

[0113] ΔM i = r i × ΔF i (26)

[0114] Then, based on the wave force and wave moment experienced by all triangular face elements, the wave force F and wave moment M of the whole ship can be calculated respectively, that is, the wave force (moment) of the whole ship can be represented as the sum of the wave force (moment) on each triangular face element as shown below:

[0115]

[0116] The coordinate and frequency transformation method is used to transform the wave force F and wave moment M of the entire ship in the stable coordinate system of the hull into the hull coordinate system, and the component arrays (F) of the overall wave force in the ship body coordinate system are obtained respectively. b , and the component array of the overall wave moment in the ship body coordinate system (M) b , and then through (F) b and (M) b The generalized wave interference force w is constructed and expressed as follows:

[0117]

[0118] Among them, (F) zb 9F) b The third term is the force in the z-axis direction in the ship's coordinate system, and (M) xb, (M0 xb for (M) b The first and second items in the equation are the moments in the x- and y-axis directions in the ship's coordinate system. In the subsequent six-degree-of-freedom dynamics study, the generalized wave disturbance force w is expressed as follows:

[0119]

[0120] The present invention also relates to a short-crest wave ocean wave dynamic response analysis system based on the finite volume method. The system corresponds to the above-mentioned short-crest wave ocean wave dynamic response analysis method based on the finite volume method, and can be understood as a system for implementing the above-mentioned method. The system includes a parameter acquisition and coordinate system establishment module, a short-crest wave wind and wave model construction module, a wave surface equation and wave height calculation module, a multi-wave superposition fluctuation pressure model acquisition module, and a generalized wave interference force calculation module, which are connected in sequence. Specifically,

[0121] The parameter acquisition and coordinate system establishment module acquires wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establishes a ground coordinate system with any point on the sea level as the origin, the ship motion direction as the longitudinal axis, the direction of the ship's starboard side and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establishes a hull stable coordinate system with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the direction of the ship's starboard side and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establishes a hull coordinate system with the ship's center of mass as the origin, the direction of the ship's bow as the longitudinal axis, the direction of the ship's starboard side as the transverse axis, and the direction of the ship's bottom as the vertical axis; the wind and wave characteristic parameters include amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave form transformation, wind and wave natural period, and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency;

[0122] The short-crested wind wave model construction module constructs a wave equation about sea wave height based on wave amplitude, wave number, main propagation direction of wind wave, propagation direction of wind wave harmonic and time of wind wave form transformation in a ground coordinate system, and obtains a short-crested wind wave model by recursion according to the wave equation;

[0123] The wave surface equation and sea wave height calculation module calculates a directional spectrum of short-crested sea wave according to the propagation direction of wind wave harmonic, constructs a first expression about long-crested sea wave energy based on wave amplitude and seawater density in the ground coordinate system, establishes an angular frequency interval according to wind wave angular frequency and frequency band width set based on the wind wave angular frequency, and then obtains a second expression about long-crested sea wave energy in the angular frequency interval, obtains a third expression about long-crested energy spectrum by recursion according to the second expression, and then calculates the long-crested energy spectrum; a short-crested wind wave spectrum is calculated according to the directional spectrum of short-crested sea wave and the long-crested energy spectrum, a fourth expression about short-crested sea wave energy is established based on the short-crested wind wave spectrum, and a first wave surface equation of short-crested wind wave is calculated according to the fourth expression and the short-crested wind wave model; then a first relationship between encounter period and encounter angular frequency is established, an angle between the ship speed direction and the main propagation direction of wind wave is taken as the ship encounter angle, a second relationship about encounter period is established based on the ship encounter angle, inherent period of wind wave, inherent wave speed of wind wave and ship speed, and a third relationship about encounter angular frequency is established based on the ship encounter angle, angular frequency of wind wave, inherent wave speed of wind wave and ship speed; the first wave surface equation in the ground coordinate system is converted into a second wave surface equation in the ship body stable coordinate system based on the first relationship, the second relationship and the third relationship, and by using coordinate and frequency transformation method, the second wave surface equation suitable for the environment around the ship is obtained, and sea wave height encountered by the ship in the navigation process is calculated according to the second wave surface equation;

[0124] The multi-wave superposition wave pressure model acquisition module calculates the depth of the sea surface from the free surface of a certain point under water according to the liquid surface depth under the static water condition and the sea wave height encountered by the ship in the navigation process in the ship body stable coordinate system, and constructs a fifth expression about the pressure of the certain point under water according to the depth of the sea surface and atmospheric pressure; a sixth expression of the pressure of the certain point under water in the short-crested sea wave condition is calculated according to the fifth expression and the short-crested wind wave model; a wave pressure model caused by sea wave is obtained according to the sixth expression, the wave pressure model is modified by using Smith correction term method to obtain a modified wave pressure model; and the modified wave pressure model is expressed as superposition of multiple cosine waves by harmonic superposition analysis method to obtain a multi-wave superposition wave pressure model;

[0125] The generalized wave disturbance force calculation module, in the ship body stability coordinate system, divides the ship into a plurality of triangular face elements based on the finite volume method, takes a vector from the ship mass center to the center of a triangular face element as a vector of the triangular face element, calculates wave fluctuation pressure of the triangular face element according to a multi-wave superposition wave fluctuation pressure model, calculates wave force of the triangular face element according to an area, a normal vector and the wave fluctuation pressure of the triangular face element, and calculates wave torque of the triangular face element according to the vector and the calculated wave force; the wave force and the wave torque of all the triangular face elements are used to calculate the wave force and the wave torque of the whole ship respectively; and the wave force and the wave torque of the whole ship in the ship body stability coordinate system are converted into the ship body coordinate system by using a coordinate and frequency conversion method, so that a component array of the wave force of the whole ship and a component array of the wave torque of the whole ship are obtained respectively, and a generalized wave disturbance force is constructed.

[0126] Preferably, in the wave surface equation and sea wave height calculation module, when the frequency band width in the third expression tends to zero, an integral expression of long-crested wave energy is calculated according to the first expression and the third expression, and a relationship between the sea wave harmonic amplitude and the spectral density function is calculated according to the integral expression.

[0127] Preferably, in the parameter acquisition and coordinate system establishment module, the wind wave characteristic parameters further include a wave length, and a wave number is calculated according to the wave length.

[0128] Preferably, the coordinate and frequency conversion method includes coordinate conversion based on a rotation matrix and conversion of wave frequency to encounter frequency.

[0129] The present application provides an objective and scientific short-crested wave dynamic response analysis method and system based on the finite volume method, a short-crested wave model is established based on characteristic parameters of wind waves and motion state parameters of a ship, a wave surface equation is obtained by using a specific calculation method and a coordinate conversion method, a multi-wave superposition wave fluctuation pressure model is obtained by using a specific correction method, and a generalized disturbance force and torque (dynamic response) are constructed based on the finite volume method, so that the dynamic response of the ship in the wind waves can be more accurately predicted, the wave force on a complex ship body can be effectively modeled and simulated, and the calculation accuracy is effectively improved.

[0130] It should be noted that the above specific embodiments can enable those skilled in the art to more fully understand the present application, but do not limit the present application in any way. Therefore, although the present application has been described in detail with reference to the drawings and examples, those skilled in the art should understand that modifications or equivalent replacements can still be made to the present application, in short, all technical solutions and improvements that do not deviate from the spirit and scope of the present application should be covered in the protection scope of the present application.

Claims

1. A method for analyzing the dynamic response of short-crest waves based on the finite volume method, characterized in that: The following steps are involved: Parameter acquisition and coordinate system establishment steps: obtain wind and wave characteristic parameters and ship motion state parameters under different sea conditions, and establish a ground coordinate system with any point on the sea level as the origin, the ship's motion direction as the longitudinal axis, the direction to the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; establish a hull stable coordinate system with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the direction to the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; A hull coordinate system is established with the ship's center of mass as the origin, the direction of the ship's bow as the longitudinal axis, the direction of the ship's starboard side as the transverse axis, and the direction of the ship's bottom as the vertical axis; the wind and wave characteristic parameters include amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave shape transformation, wind and wave natural period, and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency; The steps for constructing a short-crest wave model are as follows: In the ground coordinate system, a plane wave equation for the wave height is established based on the wave amplitude, wave number, main propagation direction of the wind wave, propagation direction of the wind wave harmonics, and the time of wind and wave shape transformation. The short-crest wave model is then obtained by recursively deducing the plane wave equation. The wave surface equation and wave height calculation steps are as follows: the directional spectrum of short-peaked waves is calculated according to the propagation direction of wind and wave harmonics, and the first expression for the energy of long-peaked waves is constructed according to the wave amplitude and seawater density under the ground coordinates. The angular frequency interval is established according to the wind and wave angular frequency and the bandwidth set based on the wind and wave angular frequency, and then the second expression for the energy of long-peaked waves within the angular frequency interval is obtained. The third expression for the energy spectrum of long-peaked waves is recursively obtained from the second expression, and then the energy spectrum of long-peaked waves is calculated; the short-peaked wave wind wave spectrum is calculated according to the directional spectrum of short-peaked waves and the energy spectrum of long-peaked waves, and the fourth expression for the energy of short-peaked waves is established based on the short-peaked wave wind wave spectrum. The fourth expression for the energy of short-peaked waves is calculated by the fourth expression and the short-peaked wave wind wave model. a wave surface equation; then, a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship speed direction and the main propagation direction of the wind and waves is taken as the ship encounter angle; a second relationship about the encounter period is established based on the ship encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship speed; and a third relationship about the encounter angular frequency is established based on the ship encounter angle, the angular frequency of the wind and waves, the natural wave speed of the wind and waves, and the ship speed; based on the first, second, and third relationships, and using the coordinate and frequency transformation method, the first wave surface equation in the ground coordinate system is converted to the hull stable coordinate system to obtain a second wave surface equation applicable to the environment surrounding the ship, and the wave height encountered by the ship during navigation is calculated according to the second wave surface equation; The steps for obtaining the multi-wave superposition fluctuation pressure model are as follows: in the ship's stable coordinate system, the sea surface depth of a certain underwater point from the free liquid surface is calculated based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation, and a fifth expression for the pressure at a certain underwater point is constructed based on the sea surface depth and atmospheric pressure; based on the fifth expression and the short-crest wave model, a sixth expression for the pressure at a certain underwater point under short-crest wave conditions is calculated; The fluctuating pressure model caused by the ocean waves is obtained according to the sixth expression, and the fluctuating pressure model is corrected by using the Smith correction term method to obtain a corrected fluctuating pressure model; and the corrected fluctuating pressure model is expressed as a superposition of multiple cosine waves by using the harmonic superposition analysis method to obtain a multi-wave superposition fluctuating pressure model; The steps of constructing the generalized wave interference force are as follows: in the stable coordinate system of the hull, the ship is divided into multiple triangular surface elements based on the finite volume method, and the vector pointing from the center of mass of the ship to the centroid of a certain triangular surface element is used as the radius vector of the triangular surface element. The wave pressure exerted on the triangular surface element is calculated according to the multi-wave superposition wave pressure model, and the wave force exerted on the triangular surface element is calculated according to the area, normal vector and wave pressure of the triangular surface element. The wave moment exerted on the triangular surface element is calculated according to the radius vector of the triangular surface element and the calculated wave force; based on the wave forces and wave moments exerted on all triangular surface elements, the wave force and wave moment of the entire ship are calculated respectively; and the coordinate and frequency transformation method is used to convert the wave force and wave moment of the entire ship in the stable coordinate system of the hull into the hull coordinate system, and the component array of the wave force of the entire ship and the component array of the wave moment of the entire ship are obtained respectively, and then the generalized wave interference force is constructed to realize the dynamic response analysis of short-peak waves.

2. The method for analyzing the dynamic response of short-crest waves based on the finite volume method according to claim 1, characterized in that: In the wave surface equation and wave height calculation steps, when the bandwidth in the third expression tends to zero, an integral expression of the long-peak wave energy is calculated based on the first expression and the third expression, and a relationship between the wave harmonic amplitude and the spectral density function is calculated based on the integral expression.

3. The method for analyzing the dynamic response of short-crest waves based on the finite volume method according to claim 1 is characterized in that: In the parameter acquisition and coordinate system establishment steps, the wind and wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

4. The method for analyzing the dynamic response of short-crest waves based on the finite volume method according to claim 1, characterized in that: The coordinate and frequency transformation method includes coordinate transformation based on rotation matrix and transformation from wave frequency to encounter frequency.

5. A short-peak wave dynamic response analysis system based on the finite volume method, characterized in that: It includes the parameter acquisition and coordinate system establishment module, the short-peak wave wind and wave model construction module, the wave surface equation and wave height calculation module, the multi-wave superposition wave pressure model acquisition module and the generalized wave interference force calculation module. The parameter acquisition and coordinate system establishment module acquires the wind and wave characteristic parameters and the motion state parameters of the ship under different sea conditions, and establishes a ground coordinate system with an arbitrary point on the sea level as the origin, the ship's motion direction as the longitudinal axis, the direction to the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; and establishes a hull stable coordinate system with the ship's center of mass as the origin, the ship's motion direction as the longitudinal axis, the direction to the starboard side of the ship and parallel to the sea level as the transverse axis, and the center of the earth as the vertical axis; A hull coordinate system is established with the ship's center of mass as the origin, the direction of the ship's bow as the longitudinal axis, the direction of the ship's starboard side as the transverse axis, and the direction of the ship's bottom as the vertical axis; the wind and wave characteristic parameters include amplitude, wave number, main propagation direction of wind and waves, propagation direction of wind and wave harmonics, wind and wave angular frequency, time of wind and wave shape transformation, wind and wave natural period, and wind and wave natural wave speed; the ship's motion state parameters include ship speed, encounter period, and encounter angular frequency; The short-crested wave wind and wave model construction module establishes a plane wave equation about the wave height based on the wave amplitude, wave number, main propagation direction of the wind and wave, propagation direction of the wind and wave harmonics, and time of wind and wave shape transformation in the ground coordinate system, and recursively obtains the short-crested wave wind and wave model based on the plane wave equation; The wave surface equation and wave height calculation module calculates the directional spectrum of short-peaked waves according to the propagation direction of wind and wave harmonics, and constructs a first expression for the energy of long-peaked waves according to the wave amplitude and seawater density in ground coordinates, establishes an angular frequency interval according to the wind and wave angular frequency and the bandwidth set based on the wind and wave angular frequency, and then obtains a second expression for the energy of long-peaked waves within the angular frequency interval, and recursively obtains a third expression for the energy spectrum of long-peaked waves from the second expression, and then calculates the energy spectrum of long-peaked waves; calculates the short-peaked wave wind wave spectrum according to the directional spectrum of short-peaked waves and the long-peaked wave energy spectrum, establishes a fourth expression for the energy of short-peaked waves based on the short-peaked wave wind wave spectrum, and calculates the energy spectrum of short-peaked waves by using the fourth expression and the short-peaked wave wind wave model. a first wavefront equation; then, a first relationship between the encounter period and the encounter angular frequency is established, and the angle between the ship's speed direction and the main propagation direction of the wind and waves is taken as the ship's encounter angle; a second relationship regarding the encounter period is established based on the ship's encounter angle, the natural period of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed; and a third relationship regarding the encounter angular frequency is established based on the ship's encounter angle, the angular frequency of the wind and waves, the natural wave speed of the wind and waves, and the ship's speed; based on the first, second, and third relationships, and using a coordinate and frequency transformation method, the first wavefront equation in the ground coordinate system is converted into the hull's stable coordinate system to obtain a second wavefront equation applicable to the ship's surrounding environment, and the wave height encountered by the ship during navigation is calculated based on the second wavefront equation; The multi-wave superposition fluctuation pressure model acquisition module calculates, in the hull stable coordinate system, the sea surface depth of a certain underwater point from the free liquid surface based on the liquid surface depth under still water conditions and the wave height encountered by the ship during navigation, and constructs a fifth expression for the pressure at the certain underwater point based on the sea surface depth and the atmospheric pressure; and calculates a sixth expression for the pressure at the certain underwater point under short-crest wave conditions based on the fifth expression and the short-crest wave model; The fluctuating pressure model caused by the ocean waves is obtained according to the sixth expression, and the fluctuating pressure model is corrected by using the Smith correction term method to obtain a corrected fluctuating pressure model; and the corrected fluctuating pressure model is expressed as a superposition of multiple cosine waves by using the harmonic superposition analysis method to obtain a multi-wave superposition fluctuating pressure model; The generalized wave interference force calculation module divides the ship into multiple triangular surface elements based on the finite volume method in a stable hull coordinate system, and uses the vector pointing from the ship's center of mass to the centroid of a certain triangular surface element as the radius vector of the triangular surface element. The wave pressure exerted on the triangular surface element is calculated according to the multi-wave superposition wave pressure model, and the wave force exerted on the triangular surface element is calculated according to the area, normal vector and wave pressure of the triangular surface element. The wave moment exerted on the triangular surface element is calculated according to the radius vector of the triangular surface element and the calculated wave force. The wave force and wave moment of the entire ship are calculated based on the wave forces and wave moments exerted on all triangular surface elements. The coordinate and frequency transformation method is used to convert the wave force and wave moment of the entire ship in the stable hull coordinate system into the hull coordinate system, and the component array of the wave force of the entire ship and the component array of the wave moment of the entire ship are obtained respectively, thereby constructing a generalized wave interference force to realize the dynamic response analysis of short-peak waves.

6. The short-crest wave dynamic response analysis system based on the finite volume method according to claim 5 is characterized in that: In the wave surface equation and wave height calculation module, when the bandwidth in the third expression tends to zero, an integral expression of the long-peak wave energy is calculated based on the first expression and the third expression, and a relationship between the wave harmonic amplitude and the spectral density function is calculated based on the integral expression.

7. The short-crest wave dynamic response analysis system based on the finite volume method according to claim 5 is characterized in that: In the parameter acquisition and coordinate system establishment step module, the wind and wave characteristic parameters also include wavelength, and the wave number is calculated based on the wavelength.

8. The short-crest wave dynamic response analysis system based on the finite volume method according to claim 5 is characterized in that: The coordinate and frequency transformation method includes coordinate transformation based on rotation matrix and transformation from wave frequency to encounter frequency.

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