Method for generating freak waves based on in-band energy transfer

Abstract

The invention provides a freak wave generation method based on in-band energy transfer. The method comprises the following steps: determining a wave surface expression of a first background wave of which the energy density distribution in each frequency band is consistent with a target energy spectrum; determining a wave surface expression of the target focused wave based on the wave making target; if the energy of the first background wave in the focusing frequency band is greater than the energy of the target focusing wave in the focusing frequency band, performing in-band energy transfer operation on the first background wave under the total energy constraint of the focusing frequency band to generate a second background wave, otherwise, the energy of the first background wave and the energy of the target focusing wave in the focusing frequency band are compared again through the target energy spectrum lifting operation or the target focusing wave updating operation; and superposing the target focused wave through the second background wave to generate the freak wave. According to the method provided by the invention, it can be ensured that the freak wave which not only meets a focused wave component amplitude target but also fits the energy distribution characteristics of actual waves can be constructed.

Description

Technical Field

[0001] This application belongs to the field of marine environment simulation technology, and relates to wave numerical simulation and modeling technology, specifically providing a method for generating distorted waves based on in-band energy transfer. Background Technology

[0002] Freak waves, also known as rogue waves, are waves that suddenly appear in the ocean with abnormally high heights. They are characterized by their sudden onset, unusual height, short duration, and unpredictability, with wave heights reaching 20-30 meters or even higher. Freak waves have a strong destructive force on marine facilities such as ships, offshore platforms, and near-shore structures. With the increasing number of large-scale marine engineering projects such as deep-sea oil and gas exploration, offshore wind farm construction, and cross-sea bridge projects, the threat of freaking waves to the safety of offshore operations is becoming increasingly prominent. Therefore, it is crucial to fully consider the impact of extreme waves during the ship design and offshore platform structural design stages.

[0003] Currently, research methods for abnormal waves mainly include actual observation, water tank experiments, and numerical simulation. However, due to the randomness and low probability of abnormal wave occurrences, obtaining sufficient abnormal wave data through actual observation is costly, time-consuming, and difficult to repeat. Experimental methods involve actively generating abnormal waves in a water tank using wave-generating plates. While this method can artificially generate abnormal waves, it is limited by equipment scale, cost, and time constraints, making large-scale parametric studies difficult. Numerical simulation directly generates abnormal waves at specific locations and times within a numerical model of a finite-volume water area, or drives a wave-generating plate model in a water tank numerical model according to preset wave-generating parameters. By numerically simulating the motion and evolution of the fluid medium model, abnormal waves generated at certain locations and times are obtained. This provides preliminary data for studying the impact of abnormal waves on ship motion response, structural loads, and platform stability. This method is low-cost, short-cycle, highly repeatable, and parameter-controllable. Furthermore, the generated data can be used for wave generation in water tank experiments, providing an effective approach for in-depth research on abnormal waves.

[0004] Generating distorted wave data using numerical simulation requires ensuring that the generated results accurately reflect the key characteristics of distorted waves under real sea conditions, such as their spectral properties, directional distribution, and nonlinearity. Otherwise, the analyzed results regarding ship response and structural loads under distorted wave action will deviate significantly from the actual situation. Currently, several distorted wave generation methods exist. For example, patent CN120012433A proposes a distorted wave generation method based on a probabilistic prediction model, and patent CN114003847A discloses a distorted wave generation modulation method and a spectral correction method. However, none of these existing methods consider the energy conversion during the generation and evolution of distorted waves, lacking meaningful physical constraints in the construction process, resulting in insufficient physical rationality and reliability of the generated distorted wave data. Summary of the Invention

[0005] The purpose of this application is to provide a method for generating distorted waves based on in-band energy transfer, which includes the following steps: S1, determine the wavefront expression of the first background wave based on the target energy spectrum, wherein the energy density distribution of the first background wave in each frequency band is consistent with the target energy spectrum; S2, determine the wave surface expression of the target focused wave based on the wave-generating target, wherein the wave-generating target includes at least the focusing time, focusing position, focusing frequency band, and wave height of each wave component of the target focused wave; S3, if the energy of the first background wave in the focusing frequency band is greater than the energy of the target focusing wave in the focusing frequency band, then perform an in-band energy transfer operation on the first background wave under the constraint of the total energy of the focusing frequency band to generate the second background wave; otherwise, return to step S3 after the target energy spectrum enhancement operation or the target focusing wave update operation. S4 generates a distorted wave by superimposing the target focusing wave with the second background wave.

[0006] The distorted wave generation method based on in-band energy transfer provided in this application starts from the physical mechanism of energy redistribution between the background wave and the focused wave under the constraint of total energy conservation during the generation and evolution of distorted waves. Under the conditions of satisfying the total energy conservation constraint of distorted waves and the wave generation target of focused waves, the form of the background wave component (i.e., the second background wave) is determined by energy appropriation within the focused frequency band. At the same time, in view of the possible conflict between the energy constraint of distorted waves and the wave generation target of focused waves, a corresponding solution is proposed to update the energy constraint condition or the wave generation target of focused waves, so as to ensure that the distorted wave that satisfies the amplitude target of focused wave components and conforms to the energy distribution characteristics of actual waves is constructed. Attached Figure Description

[0007] Figure 1 This is a flowchart of a distortion wave generation method based on in-band energy transfer provided in an embodiment of this application; Figure 2 This is a schematic diagram of a wave power density function for constructing a first background wave according to an embodiment of this application; Figure 3 This is a schematic diagram of the wavefront sequence of a first background wave in the range of 0s-100s according to an embodiment of this application; Figure 4 for Figure 3 A schematic diagram of the wavefront sequence of the first background wave in the range of 80s-100s; Figure 5 This is a schematic diagram of a wavefront sequence of a target focused wave in the range of 80s-100s according to an embodiment of this application; Figure 6 This is a schematic diagram of the energy spectrum distribution of a first background wave and a target background wave according to an embodiment of this application; Figure 7 This is a schematic diagram of a wavefront sequence of a second background wave in the range of 80s-100s according to an embodiment of this application; Figure 8 This is a schematic diagram illustrating the principle of a target energy spectrum enhancement operation according to an embodiment of this application; Figure 9 This is a schematic diagram illustrating the principle of a target focusing wave update operation according to an embodiment of this application; Figure 10 This is a schematic diagram of a wavefront sequence of a distorted wave in the range of 80s-100s according to an embodiment of this application. Detailed Implementation

[0008] The present application will be further described below based on preferred embodiments and with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments in the present application without creative effort are within the scope of protection of the present application.

[0009] To clearly illustrate the improvements of the technical solution of this application compared with the prior art, we will first briefly introduce the current methods for generating distorted waves based on wave spectrum characteristics.

[0010] Patent CN114003847A discloses a method for generating and modulating distorted waves and a method for correcting their spectrum. The technical solution adopted by this method first constructs an irregular wave sequence, then constructs an extreme wave, and then multiplies it with a transition function in the time domain according to different scaling factors, which are used as weights for the irregular wave sequence and a single extreme large wave sequence, respectively. The two are then weighted and superimposed to construct a wave sequence containing distorted waves.

[0011] The construction mechanism of this distorted wave treats irregular waves and extreme waves as two independent processes and linearly accumulates them. Because it does not consider the coupling relationship between extreme waves and the background irregular waves during their evolution, it is not constrained by energy conservation when adjusting the scaling factor. This causes the wave spectrum of the constructed distorted wave to deviate from the expected wave spectrum in terms of energy distribution. Furthermore, since a scaling factor is required during the linear superposition of the irregular wave sequence and the single maximum wave sequence, the extreme wave component in the final distorted wave may not meet the expected target. Therefore, although this method considers the simultaneous existence of irregular waves and extreme large waves in the distorted wave, its linear weighted superposition mechanism determines that the energy characteristics of the extreme wave component and the wave spectrum characteristics of the entire distorted wave cannot simultaneously meet the preset target. The specific reasons can be briefly analyzed as follows: Suppose the wave is any on the coastal plane Propagation along the axial direction, its wavefront It can be expressed as the superposition of multiple wave components in equation (1): (1), in, , These are location variables and time variables, respectively. The total number of wave components that make up the overall wavefront. , , , These are the first and second waves that make up the overall wavefront. The wave height, wave number, angular frequency, and random phase of each wave component. Clearly, and That is, to constitute The lower and upper frequency limits of each wave component, when adjacent wave components are spaced at equal angular frequencies. When the superimposed wave bandwidth is... , The wave height can be obtained by solving the dispersion equation. The value can be determined according to The power spectrum followed by the wavefront is represented or energy spectrum Sure.

[0012] When multiple wave components are exactly in phase at a certain point in time and space, constructive interference will occur, forming a local maximum (i.e., a focused wave part with concentrated energy), thus producing a distorted wave phenomenon. In order to analyze the formation mechanism of the distorted wave, the wavefront can be decomposed according to the form of equation (2): (2), in, The superposition effect of wave components that contribute little to the local maximum shape in the distorted wave is used to characterize the background wave field. This represents the focused wave component that is phase-aligned within the focused spatiotemporal region and plays a dominant role in the extreme wave height.

[0013] It should be noted that equation (2) is actually a "post-hoc statistical decomposition" method used to analyze the formation and evolution mechanism of distorted waves. In fact, when using this equation to characterize distorted waves, it is also necessary to note that the background wave component, the focused wave component, and the energy of the total wave are constrained by the following nonlinear relationship: (3), (3) In the formula, , The energy spectra of the background wave component and the focused wave component are respectively. This represents the total energy spectrum of waves in the extreme wave region. The overall phase difference between the background wave and the focused wave. This reflects the overall coherence intensity between the background wave and the focused wave. Because the phases of the various wave components of the background wave are random, its overall coherence with the focused wave is relatively small. The absolute value is generally much less than 1.

[0014] Within the framework of linear wave theory, the energy spectrum of waves In other words, the energy of waves per unit frequency interval and per unit sea surface area, and the power spectral density of the wave surface, which is also the variance spectral density. There is usually a linear proportional relationship between them: (4), in, For wavefront variance, , These are the density of water and the acceleration due to gravity, respectively.

[0015] Observing equations (3) and (4), it can be seen that when analyzing distorted waves, although the wave surface morphology... The distorted wave can be considered as being composed of background wave components superimposed with focused wave components, but from an energy perspective, the energies of both the background wave and the focused wave are similar. Related, and the total energy spectrum It contains the energy spectra of the background wave energy component and the focused wave energy component, respectively. , It also includes nonlinear coupling terms of energy components. The sum of these three satisfies the law of conservation of energy.

[0016] Because of the conservation constraint of the wavefront amplitude term due to the nonlinear superposition of energy terms, the generation of distorted waves can be directly achieved using equation (2), or by using the transition function. Weighted superposition of background and focused waves, for example, by means of a form such as The expression generates distorted waves, not only in regulating The process cannot follow the law of conservation of energy, and also has the following problems: (1) If energy constraints are not considered, for Setting the component to a higher value will result in an energy portion containing focused wave components. + In the total energy spectrum of the distorted wave The proportion of energy in the middle is too high, which causes the energy of local frequency bands in the total energy spectrum to be artificially raised to a level that is not physically reasonable. (2) If the physical reliability of the total energy spectrum is improved by reducing the proportion of the focused wave component in the wave surface equation, the wave height of the focused wave will inevitably be lower than the preset target wave height, resulting in the focused wave component in the final generated distorted wave failing to meet the expected index.

[0017] It is evident that due to the nonlinear energy constraints caused by the multi-component combination of waves, directly constructing distorted waves containing background components from the wave surface morphology is difficult to balance wave morphology and energy distribution. Therefore, it is necessary to start from the physical mechanism of energy redistribution between background waves and focusing waves under the constraint of total energy conservation during the generation and evolution of distorted waves in order to construct extreme waves that satisfy the amplitude target of focusing wave components and conform to the energy distribution characteristics of actual waves.

[0018] Therefore, this application proposes a method for generating distorted waves based on in-band energy transfer. Figure 1 A flowchart of the distorted waveform data generation method provided according to some embodiments of this application is shown, such as... Figure 1 As shown, the method includes the following steps: S1, determine the wavefront expression of the first background wave based on the target energy spectrum, wherein the energy density distribution of the first background wave in each frequency band is consistent with the target energy spectrum; S2, determine the wave surface expression of the target focused wave based on the wave-generating target, wherein the wave-generating target includes at least the focusing time, focusing position, focusing frequency band, and wave height of each wave component of the target focused wave; S3, if the energy of the first background wave in the focusing frequency band is greater than the energy of the target focusing wave in the focusing frequency band, then perform an in-band energy transfer operation on the first background wave under the constraint of the total energy of the focusing frequency band to generate the second background wave; otherwise, perform a target energy spectrum enhancement operation or a target focusing wave update operation and return to step S3. S4 generates a distorted wave by superimposing the target focusing wave with the second background wave.

[0019] Unlike existing methods that directly perform linear weighted superposition of irregular wave (background wave) and extreme wave (focused wave) wavefront expressions, the deformed wave generation method provided in this application starts from satisfying energy conservation constraints and redistributes the energy of the background wave and the preset focused wave. Its implementation idea is based on the following considerations: At a specific spatiotemporal location (i.e., the focused spatiotemporal location), wave components in certain frequency bands (i.e., the focused frequency band) undergo constructive phase interference, causing a significant change in the proportion of energy of randomly superimposed background wave components and the energy of focused wave components superimposed in the same phase within the focused spatiotemporal location and the focused frequency band, ultimately resulting in a distorted wave surface morphology.

[0020] Meanwhile, considering the conservation of total wave energy during the formation and evolution of the focused wave, this physical constraint should be followed as much as possible when constructing the distorted wave. To this end, in step S1, the target energy spectrum of the final distorted wave is first set, and it is initially assumed that the wave corresponding to this energy spectrum is entirely composed of the initial background wave (i.e., the first background wave), at which point the focused wave component energy is zero. Then, in step S2, the target focused wave form to be generated is determined. Then, in step S3, according to the energy requirement for generating the target focused wave within the preset focusing frequency band, the corresponding energy is "allocated" from the first background wave to the focused wave component within the focusing frequency band, thereby obtaining the background wave form after energy redistribution. Through this energy transfer and redistribution operation under the constraint of total energy conservation, the background wave form (i.e., the second background wave) that ensures the preset focused wave generation target can be generated under the premise of meeting the total energy budget.

[0021] Meanwhile, if in step S3 it is determined that the energy of the first background wave within the focusing frequency band is insufficient to support the preset focusing wave generation requirement, it indicates a conflict between the total energy target and the focusing target set in steps S1 and S2. In this case, it is necessary to adjust the target energy spectrum or change the wave generation target of the focusing wave to ensure that the background wave component and the focusing wave component in the final generated distorted wave can satisfy the energy conservation constraint. Therefore, the method provided in this application can determine in advance whether the preset focusing wave generation target conforms to the overall energy distribution characteristics of the wave, and provide an adjustment method that conforms to the physical picture for the conflict between the two.

[0022] The specific implementation methods of steps S1 to S4 are explained in detail below.

[0023] <Generate the first background wave> Step S1 is used to determine the form of the first background wave that conforms to the target energy spectrum distribution characteristics. As analyzed above, the first background wave reflects the wave pattern in the absence of a focusing wave. In the energy transfer operation described later, the energy of the first background wave in the focusing frequency band can be regarded as the "energy source" of the focusing wave.

[0024] In some specific embodiments, the wavefront expression of the first background wave can be established first. : (5), in, , These are location variables and time variables, respectively. The total number of wave components constituting the first background wave, , , , The first background wave is the first The wave height, wave number, angular frequency, and random phase of each wave component can be found in the explanation of equation (1). Similarly, , The lower and upper limits of the angular frequency of the first background wave are defined as follows: without loss of generality, adjacent wave components in the first background wave also use equal angular frequency intervals. , That is, the bandwidth of the first background wave. .

[0025] Then, based on various wave power density functions known to those skilled in the art, such as the PM spectrum (Pierson-Moskowitz spectrum), JONSWAP spectrum, and Bretschneider spectrum, the target power spectral density function is determined. Then, based on the linear proportional relationship between the power spectral density and the energy spectrum, the corresponding target energy spectrum is obtained. : (6), in, This is the proportionality coefficient, generally speaking. , For the density of water, This is the acceleration due to gravity.

[0026] Finally, based on the target energy spectrum The angular frequencies of each wave component of the first background wave The value at that point determines the amplitude of each wave component. This ultimately generates the wavefront expression for the first background wave. .

[0027] Figure 2 This illustrates, in a specific embodiment, the power density spectral function used to construct the first background wave. Figure 3 The diagram shows a specific wavefront of a first background wave generated through the above steps, with a time range of 0s-100s. Figure 4 right Figure 3 The first background wave in the image is magnified and displayed in the 80s-100s range.

[0028] It should be noted that, due to the linear proportional relationship between power spectral density and energy spectrum, in some optional embodiments, it is also possible to base it on... Wavefront expression for generating the first background wave Therefore, it is only necessary to determine the values ​​of each wave component based on the power spectral density function when generating the target focused wave in the subsequent process.

[0029] <Generate target focused wave> Step S2 is used to generate a target focused wave, which represents the focused wave component expected to be included in the final generated distorted wave. In this application, the wavefront expression of the target focused wave is... for: (7), in, , , The first wave in the target focusing wave Wave height, wave number, and angular frequency of each wave component. and These represent the focusing position and focusing time of the target focused wave, respectively. , These are the minimum and maximum indices of the wave components that constitute the focused wave of the target, respectively. , This refers to the lower and upper limits of the focused frequency band, which in turn determines the focused bandwidth. .

[0030] Without loss of generality, the adjacent wave components of the target focusing wave also adopt equal frequency intervals. Furthermore, when the energy spectrum of the target focused wave is set in a mirror-symmetric manner from the peak frequency to both sides, the peak angular frequency of the target focused wave is easily obtained. .

[0031] Obviously, generating the target focusing wave based on equation (8) means determining the value in equation (8) according to the preset wave-generating target. , , , as well as The specific value to be taken.

[0032] (1) Determine the focusing position and focusing time.

[0033] In some specific embodiments, the specific location and time at which the distorted wave is formed by wave focusing can be selected based on numerical simulation or the target of wave generation in the experimental water tank, thereby obtaining... , The specific value to be taken.

[0034] (2) Set the focusing frequency band.

[0035] Focused bandwidth The focusing bandwidth of the target focused wave can be determined based on the energy distribution characteristics of the distorted wave that needs to be studied or manufactured. Generally much smaller than the bandwidth of the first background wave. Its energy is concentrated at the peak angular frequency. Nearby, for example, in some alternative embodiments, may As the center of the focused frequency band, As the lower limit of the focused frequency band ,by As the upper limit of the target frequency band When it is necessary to study or create distorted waves with energy concentrated near the peak frequency, the coefficient can be... Set it to a smaller value, for example, let This allows the energy of the focused wave to be concentrated in... Surrounding areas; when it is necessary to study or create distorted waves with a wide frequency distribution of energy, the coefficient can be appropriately increased. The value, for example Or even larger.

[0036] (3) Determine the wave height of each wave component.

[0037] Wave height of each wave component that constitutes the target focusing wave This reflects the energy magnitude of the target-focused wave, which can be determined using various methods known to those skilled in the art. The specific value can be determined. For example, in some optional embodiments, time-series data containing distorted waves can be extracted from actual sea surface elevation measurements, and spectral analysis can be performed on them to obtain the power spectrum or energy spectrum of the measured sea surface. The spectral analysis results will be used as... Establish empirical values ​​or references for setting up a target focused wave that conforms to the characteristics of real sea surface distortion waves; In some alternative embodiments, known virtual wave generation theories such as New Wave can be used to select specific wave power spectra or energy spectra to characterize the energy distribution of the target focusing wave at various frequencies, and then the wave height of each wave component constituting the target focusing wave can be determined based on the total energy conservation.

[0038] Determined through the above steps , , , , After determining the specific values, substitute each parameter value into equation (7) to determine the wave surface expression of the target focusing wave. Figure 5 The diagram illustrates the wavefront of the target focused wave generated through the above steps in a specific embodiment within the range of 80s-100s. As can be seen from the preceding analysis, in the method of this application, the wavefront morphology of the target focused wave is no longer adjusted when the first background wave can provide sufficient energy support, to ensure that the ultimately generated distorted wave contains a focused wave component of the desired amplitude.

[0039] <Internal Energy Transfer Operation> Step S3 is the core step of the wave generation method provided in this application, such as... Figure 1 As shown, in this step, the energy of the first background wave and the target focused wave in the focusing frequency band is first calculated. According to the calculation results, if the energy of the first background wave in the focusing frequency band can provide support for the target focused wave, then the energy contained in the first background wave is allocated to the target focused wave according to the energy requirements of the target focused wave. Then, under the constraint of total energy conservation, the wavefront expression of the background wave in the focusing frequency band (i.e., the second background wave) is updated according to the result of energy redistribution.

[0040] Since the energy transfer operation is based on the energy ratio of the background wave and the target focused wave, it is only necessary to obtain the energy ratio to determine the energy magnitude and perform the redistribution operation. Considering that at the spatiotemporal location where wave focusing occurs, the energy of each wave component can be determined based on its wave height, in some specific embodiments, the first background wave is in the focusing frequency band. Internal energy and the target focused wave in the focusing frequency band Internal energy It can be calculated using equations (8) and (9): (8), (9), See equations (5) and (7) for details. , These are the minimum and maximum indices of the wave components that constitute the focused wave of the target, respectively. The first background wave The wave height of each wave component Focusing on the target wave The wave height of each wave component.

[0041] It should be understood that, in some embodiments, the energy calculation method within the focusing frequency band shown in equations (8) and (9) can also be replaced with other optional forms. For example, the area enclosed by the energy spectrum curves of the first background wave and the target focusing wave within the focusing frequency band can be calculated by integration to characterize the energy levels of the two within the focusing frequency band.

[0042] when This indicates that, under the current target energy spectrum and target focusing wave settings, the energy of the first background wave within the focusing frequency band is sufficient to provide energy support for constructing the target focusing wave. For example, like... Figure 6 As shown, the area covered by the target energy spectrum in the focusing frequency band is larger than the area covered by the energy spectrum of the target focused wave in the focusing frequency band. Therefore, the percentage of remaining energy that is allocated to the background wave can be determined by energy transfer operation, under the premise of satisfying the energy requirements of the target focused wave and the conservation of total energy. Based on the energy redistributed to the background wave, the wavefront form that the background wave should have can be re-determined.

[0043] In some specific embodiments, the in-band energy transfer operation includes the following steps: The first step is to solve the equation shown below to obtain the energy of the second background wave within the focusing frequency band. : (10) in, and As mentioned earlier, these represent the energy of the first background wave within the focusing frequency band and the energy of the target focusing wave within the focusing frequency band, respectively. This is a reflection , The coefficient of coherence between them.

[0044] It is understandable that the equation shown in (10) is a reflection of the energy relationship between the components in the distorted wave shown in (3) within the focusing frequency band, where, The adjustable correlation coefficient reflects the overall coherence intensity between the updated second background wave (within the focusing band) and the target focused wave. As mentioned earlier, due to the random phase distribution of each wave component in the background wave, the coherence between the second background wave and the target focused wave is generally small. It should be much less than 1.

[0045] For example, in some specific embodiments, it can be Set to 0, that is At this point, the energy of the target focused wave can be obtained by subtracting the energy of the first background wave within the focusing frequency band. .

[0046] In some other specific embodiments, it is possible to make Take non-zero values ​​and limit ,For example This results in a weaker coherence between the background wave component and the focused wave component in the final generated distorted wave.

[0047] The second step is to determine the compression factor based on the following formula. : (11).

[0048] The third step is to determine the wave height of each background wave component within the focusing frequency band after energy transfer based on the following formula. : (12).

[0049] Fourth step: Generate the second background wave based on the following formula. : (13).

[0050] Specifically, in each of the above steps, firstly, by solving the equation shown in equation (10), it is determined how much energy remains to construct the background wave after diverting energy from the focusing frequency band of the finally generated distorted wave to meet the construction target of the focusing wave. Then, by calculating the ratio of the remaining energy to the background wave energy before it was diverted, and taking into account the square relationship between energy and wave height, the compression factor shown in equation (11) is obtained. Then, the wave height of the background wave within the focusing frequency band is compressed using a compression factor to obtain the wave height of each wave component of the background wave within the focusing frequency band. ; Use last The wave surface expression of the background wave within the focusing frequency band is updated. It can be understood that the wave number, angular frequency and phase of each wave component of the background wave within the focusing frequency band do not need to be changed, and the expression of the background wave outside the focusing frequency band remains unchanged. Finally, the second background wave shown in equation (13) is obtained, which simultaneously satisfies the wave generation target of the focusing wave and the conservation of total energy.

[0051] Figure 7 The figure shows the wavefront of the second background wave generated by in-band energy transfer in the range of 80s-100s in one specific embodiment. For comparison, the figure also shows the wavefront of the original first background wave.

[0052] <Handling methods when wave generation targets conflict with energy spectrum targets> If the calculation obtained in step S3 This indicates a conflict between the target energy spectrum and the target focused wave determined in steps S1 and S2 respectively. Therefore, a distorted wave conforming to the physical image cannot be generated based on the current target (it should be particularly noted that...). This means that all the energy of the background wave needs to be diverted to the focused wave, resulting in the generated distorted wave lacking irregular background wave components within the focusing frequency band, which clearly does not conform to the wave surface composition of a real wave.

[0053] In the embodiments of this application, the target energy spectrum of the distorted wave determined in step S1 can be changed by the target energy spectrum lifting operation, or the target focusing wave generation target determined in step S2 can be changed by the target focusing wave updating operation, so as to resolve the problem of conflict between the two targets.

[0054] a. Target energy spectrum enhancement operation In some specific embodiments of this application, the target energy spectrum enhancement operation includes the following steps: Step A1: Optimize the overall energy spectrum of the current target.

[0055] Specifically, it can be done in the current target energy spectrum. Add a constant to To obtain the updated target energy spectrum: ; In this way, the energy of each frequency band can be raised as a whole without changing the shape of the target energy spectrum. Figure 8 The changes in the target energy spectrum before and after the elevation are shown in one embodiment.

[0056] Step A2: Based on the target energy spectrum after overall lifting, redetermine the wavefront expression of the first background wave.

[0057] Clearly, by performing a target energy spectrum enhancement operation, the wave heights of all wave components of the regenerated first background wave within the focusing frequency band will be increased, thus increasing the energy... Increase accordingly, when it reaches After that, the in-band energy transfer operation can be performed, if it has been lifted. Still less than or equal to Then the target energy spectrum lifting operation can be repeated until an in-band energy transfer operation can be performed.

[0058] b. Target-focused wave update operation The target focusing wave update operation resolves target conflicts by changing the target focusing wave determined in step S2 without altering the energy spectrum of the final generated distorted wave.

[0059] In some alternative embodiments, the target-focused wave update operation is achieved by reducing the overall energy of the target-focused wave, for example, when the wave height of each wave component of the target-focused wave is reduced. When determined based on measured data, the wave height of each wave component can be determined. Subtract constant from all The wavefront expression of the target-focused wave is redefined. As the energy of each wave component of the target-focused wave decreases, the energy of the reconstructed target-focused wave... Become smaller At this time, an in-band energy transfer operation can be performed; for example, when the target focused wave is constructed based on a preset energy spectrum, an operation opposite to the target energy spectrum enhancement operation can be performed, and the wavefront expression of the target focused wave is redefined after the overall energy spectrum of the constructed target focused wave is reduced. Become smaller At that time, in-band energy transfer operations can be performed.

[0060] In some alternative embodiments, the target focusing wave update operation can also be implemented by widening the focusing bandwidth; specifically, the current focusing bandwidth can be widened. ~ The focus is extended to both sides to obtain new focusing frequency bands, and then the wavefront expression of the target focused wave is redefined based on the new focusing frequency bands.

[0061] Figure 9 This illustration shows a comparison of the target energy spectrum and the target focused wave energy spectrum before and after focusing bandwidth widening in one embodiment. It can be understood that the first background wave and the target focused wave have different focusing bandwidths. The energy contained in all frequencies will increase after the addition, but because the energy spectrum of the focused wave is much sharper than that of the background wave, the energy increase of the first background wave is significantly greater than the energy increase of the target focused wave in the newly added frequency bands on both sides. Therefore, it can also be... Raise to greater than The degree of.

[0062] <Generate the final distorted wave> In step S4, the current target focusing wave is directly focused. Second background wave By superposition, the wavefront expression of the final generated distorted wave can be obtained. : (14).

[0063] Figure 10The wavefront of the deformed wave in the range of 80s-100s is shown in one embodiment. The wavefront expression shown in equation (14) can be used to simulate the generation and evolution of deformed waves at any location and their impact on ships and offshore facilities. It can also be used as the basis for sending control commands to the wave-generating plate when deformed waves are generated in an experimental water tank.

[0064] The specific embodiments of this application have been described in detail above. For those skilled in the art, several improvements and modifications can be made to this application without departing from the principle of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for generating distorted waves based on in-band energy transfer, comprising the following steps: S1, determine the wavefront expression of the first background wave based on the target energy spectrum, wherein the energy density distribution of the first background wave in each frequency band is consistent with the target energy spectrum; S2, determine the wave surface expression of the target focused wave based on the wave-generating target, wherein the wave-generating target includes at least the focusing time, focusing position, focusing frequency band, and wave height of each wave component of the target focused wave; S3, if the energy of the first background wave in the focusing frequency band is greater than the energy of the target focusing wave in the focusing frequency band, then perform an in-band energy transfer operation on the first background wave under the constraint of the total energy of the focusing frequency band to generate the second background wave; otherwise, return to step S3 after the target energy spectrum enhancement operation or the target focusing wave update operation. S4 generates a distorted wave by superimposing the target focusing wave with the second background wave.

2. The method for generating distorted waves based on in-band energy transfer according to claim 1, characterized in that, Wave surface expression of the first background wave for: ， in, , These are location variables and time variables, respectively. The total number of wave components constituting the first background wave, , , , The first background wave is the first The wave height, wave number, angular frequency, and random phase of each wave component, and the wave height of each wave component. Based on the angular frequencies of each wave component of the target energy spectrum The value at that location is determined.

3. The method for generating distorted waves based on in-band energy transfer according to claim 2, characterized in that, The wavefront expression of the target focused wave for: ， in, , , The first wave in the target focusing wave Wave height, wave number, and angular frequency of each wave component. and These represent the focusing position and focusing time of the target focused wave, respectively. , These are the minimum and maximum sequence numbers of the wave components that constitute the focused wave of the target, respectively.

4. The method for generating distorted waves based on in-band energy transfer according to claim 3, characterized in that, In-band energy transfer operations include the following steps: The first step is to solve the equation shown below to obtain the energy of the second background wave within the focusing frequency band. : ， in, The energy of the first background wave within the focusing frequency band. The energy of the target focused wave within the focusing frequency band. To reflect , The coefficient of coherence between them; The second step is to determine the compression factor based on the following formula. : ； The third step is to determine the wave height of each background wave component within the focusing frequency band after energy transfer based on the following formula. : ； Fourth step: Generate the second background wave based on the following formula. : 。 5. The method for generating distorted waves based on in-band energy transfer according to claim 4, characterized in that, The energy of the first background wave within the focusing frequency band The energy of the target focused wave within the focusing frequency band They are respectively: ， 。 6. The method for generating distorted waves based on in-band energy transfer according to claim 4, characterized in that, The absolute value is less than or equal to 0.

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7. The method for generating distorted waves based on in-band energy transfer according to claim 4, characterized in that, The target energy spectrum enhancement operation includes the following steps: A1, to raise the overall energy spectrum of the current target; A2, based on the target energy spectrum after overall lifting, redetermine the wavefront expression of the first background wave.

8. The method for generating distorted waves based on in-band energy transfer according to claim 4, characterized in that, The target focusing wave update operation is achieved by reducing the overall energy of the target focusing wave, specifically: When the wave heights of each wave component of the target focused wave are determined based on measured data, a constant is subtracted from the wave height of each wave component, and the wave surface expression of the target focused wave is redefined; or, when the target focused wave is constructed based on a preset energy spectrum, the energy spectrum of the constructed target focused wave is reduced as a whole, and the wave surface expression of the target focused wave is redefined.

9. The method for generating distorted waves based on in-band energy transfer according to claim 4, characterized in that, The target focusing wave update operation is achieved by widening the focusing frequency band, specifically: The current focusing frequency band is extended to both sides to obtain a new focusing frequency band, and then the wavefront expression of the target focusing wave is redefined based on the new focusing frequency band.

10. The method for generating distorted waves based on in-band energy transfer according to claim 9, characterized in that, When the target focused wave is updated by widening the focusing bandwidth, the energy contained in both the first background wave and the target focused wave increases after the focusing bandwidth is increased, and the energy increase of the first background wave is greater than the energy increase of the target focused wave.

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