A simulation method and system for simulating the hoisting and lowering of an object into water by a crane ship

Abstract

The present disclosure provides a simulation method and system for simulating the lowering of an object into water by a crane ship. The method includes the following steps: constructing an underwater entry analysis model including a pool model and an object model according to the obtained pool parameters and object parameters; performing mesh division on the underwater entry analysis model according to preset mesh parameters to form an underwater entry analysis simulation environment; in the simulation environment, simulating the falling of the object model in the pool model according to the obtained simulation environment parameters and the object lowering trajectory, and constraining the update of the velocity and displacement through a rigid body motion solver to simulate the process of the crane ship lowering the object into water, so as to obtain the free surface distribution and pressure distribution during underwater entry. It can more accurately simulate the process of the crane ship lowering the object into water, calculate the changes in the cavity when a cylinder enters the water, and analyze the influence of the cavity on the force on the object. The research based on this model can provide data guidance for the design of the crane control system.

Description

Technical Field

[0001] The present disclosure relates to the technical field related to object entry into water analysis, and more specifically, to a simulation method and system for simulating the entry of an object into water by a crane vessel. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] In the case of severe sea conditions, it is an extremely important issue in marine engineering to safely and stably lift cargo into the seawater for engineering construction. When the load passes through the splash zone, it will be subject to great hydrodynamic effects, causing the load to sway and increase the risk of collision with the hull. In addition, the presence of the cavity will suddenly increase the force on the cable, increasing the risk of cable breakage. All of these have brought great challenges to the design of the control system of the deep-sea crane. Therefore, before designing the crane control system, it is urgent to propose a reasonable model to analyze the process of free fall of objects into the wave.

[0004] The inventors found that the existing analysis methods use physical entities, which is very time-consuming, and the data will be affected by various external constraints. In addition, the motion solver built into OpenFOAM can only solve simple six-degree-of-freedom object motions. It cannot simulate the process of a load being lifted from a crane ship, fixed in the air, lowered at a constant speed under the constraints of cables, and then freely falling into the water. It cannot provide accurate data for the design of the control system of a deep-sea crane. Summary of the invention

[0005] In order to solve the above problems, the present disclosure proposes a simulation method and system for simulating a crane vessel lifting an object into water, which can simulate the process of a crane lifting an object and the free fall of the object into the waves, and can simulate the force changes and the distribution of the free liquid surface when the object is lifted by the crane into the waves.

[0006] In order to achieve the above objectives, the present disclosure adopts the following technical solutions:

[0007] One or more embodiments provide a simulation method for simulating a crane vessel dropping an object into water, comprising the following steps:

[0008] According to the acquired pool parameters and object parameters, a water entry analysis model including a pool model and an object model is constructed;

[0009] The water entry analysis model is meshed according to preset mesh parameters to form a water entry analysis simulation environment;

[0010] In the simulation environment, the object model is simulated falling in the pool model according to the obtained simulation environment parameters and the object lifting trajectory. The rigid body motion solver constrains the update of velocity and displacement to simulate the process of the crane lifting the object into the water, and the free surface distribution and pressure distribution of the object entering the water are obtained.

[0011] One or more embodiments provide a simulation system for simulating a crane vessel placing an object into water, comprising:

[0012] A construction module is configured to construct a water entry analysis model including a water pool model and an object model according to the acquired water pool parameters and object parameters;

[0013] A grid division module is configured to perform grid division on the water entry analysis model according to preset grid parameters to form a water entry analysis simulation environment;

[0014] The simulation execution module is configured to simulate the falling of the object model in the water pool model according to the obtained simulation environment parameters and the object lifting trajectory in the simulation environment, and to simulate the process of the crane vessel lifting the object into the water by updating the velocity and displacement constraints of the rigid body motion solver to obtain the free surface distribution and pressure distribution of the object entering the water.

[0015] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps described in the above method are completed.

[0016] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the steps described in the above method are completed.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The method proposed in this disclosure, as well as the solver updated according to the constraint speed and displacement of the process of the crane ship hoisting the object into the water, can more accurately simulate the process of the crane ship hoisting the object into the water, calculate the changes in the cavity when the cylinder enters the water, and analyze the influence of the cavity on the force of the object. Research based on this model can provide data guidance for the design of crane control systems.

[0019] The advantages of the present disclosure and the advantages of additional aspects will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and the description thereof are used to explain the present disclosure but do not constitute a limitation of the present disclosure.

[0021] Figure 1It is the flowchart of the method in Embodiment 1 of the present disclosure;

[0022] Figure 2 It is the water entry analysis model in Embodiment 1 of the present disclosure;

[0023] Figure 3 It is the schematic diagram of the model grid distribution in Embodiment 1 of the present disclosure;

[0024] Figure 4(a) is the grid distribution of the sub-grid in Embodiment 1 of the present disclosure;

[0025] Figure 4(b) is the comparison between the free liquid surface when the cylinder enters the water obtained by using the water entry analysis model in Embodiment 1 of the present disclosure and the free liquid surface obtained from experimental data;

[0026] Figure 5(a) is the variation of the vertical force on the cylinder with the water entry time in the simulation experiment of Embodiment 1 of the present disclosure;

[0027] Figure 5(b) is the variation of the horizontal force on the cylinder with the water entry time in the simulation experiment of Embodiment 1 of the present disclosure;

[0028] Figure 6 It is the free liquid surface distribution during the process of the cylinder entering the water in the simulation experiment of Embodiment 1 of the present disclosure;

[0029] Figure 7 It is the pressure distribution on the surface of the cylinder in the simulation experiment of Embodiment 1 of the present disclosure;

[0030] Figure 8 It is the wave entry position in the simulation experiment of Embodiment 1 of the present disclosure;

[0031] Figure 9(a) is the variation of the vertical force when the cylinder enters the water at different wave positions in the simulation experiment of Embodiment 1 of the present disclosure;

[0032] Figure 9(b) is the variation of the horizontal force when the cylinder enters the water at different wave positions in the simulation experiment of Embodiment 1 of the present disclosure. Detailed implementation manners

[0033] The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further descriptions of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present disclosure belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and the features in the embodiments of the present disclosure can be combined with each other. The embodiments will be described in detail below with reference to the drawings.

[0036] Embodiment 1

[0037] In the technical solutions disclosed in one or more embodiments, as Figure 1 shown, a simulation method for simulating the hoisting of an object into water by a crane ship includes the following steps:

[0038] Step 1: According to the obtained pool parameters and object parameters, construct an underwater entry analysis model including a pool model and an object model;

[0039] Step 2: Perform mesh division on the underwater entry analysis model according to the preset mesh parameters to form an underwater entry analysis simulation environment;

[0040] Step 3: In the simulation environment, according to the obtained simulation environment parameters and the object hoisting trajectory, simulate the falling of the object model in the pool model, and constrain the update of velocity and displacement through a rigid body motion solver to simulate the process of the crane ship hoisting the object into water, and obtain the free surface distribution and pressure distribution of the underwater entry.

[0041] The simulation results obtained in this embodiment can be used to analyze the force analysis of the load when the crane hoists the load into water, so as to select a suitable underwater entry speed and underwater entry timing for the crane control system. Some special phenomena such as the sharp hydrodynamic changes caused by cavities will also provide guidance for the design of the crane control system.

[0042] The method proposed in this embodiment, as well as the solver that constrains the update of velocity and displacement according to the process of the crane ship hoisting the object into water, can more accurately simulate the process of the crane ship hoisting the object into water, calculate the changes in the cavity when the cylinder enters the water, and analyze the influence of the cavity on the force of the object. The research based on this model can provide data guidance for the design of the crane control system.

[0043] Optionally, the pool parameters include the pool shape, size, wave parameters, etc. The wave parameters include wave size, shape, propagation speed, etc.

[0044] Optionally, the object parameters are the parameters of the object entering the water, including size, shape, density, etc.

[0045] Optionally, the object motion parameters include the object's water entry speed, water entry position, motion trajectory, etc. The simulation environment parameters may include pool parameters, object parameters, and object motion parameters.

[0046] The water-entry object can be an object of any shape, such as a cuboid, a cylinder, etc. Hereinafter, the water entry of a cylindrical object will be taken as an example for illustration.

[0047] In step 1, the water entry analysis model includes an object model and a pool model. It can be as Figure 2 shown.

[0048] Optionally, the pool model can be set to any shape, such as a rectangle, which is divided into zones, including a wave generation zone and an impact zone.

[0049] The wave generation zone is configured to generate simulated waves, which are generated by setting a wave-making boundary. The impact zone is the area where the object model enters the water.

[0050] In this embodiment, as Figure 2 shown, the waves are generated by the wave-making boundary on the left side, and the wave propagation direction is to the right. The wave-making boundary can generate different types of waves, such as solitary waves, Stokes regular waves, irregular waves, etc.

[0051] Optionally, the wave-making boundary can form waves by setting the liquid velocity at the boundary, and can generate Stokes second-order regular waves. The formula for the wave velocity distribution is:

[0052]

[0053]

[0054] where u(x,z,t) and w(x,z,t) are the horizontal and vertical components of the wave velocity respectively. H is the wave height of the wave, ω is the angular frequency of the wave, and h is the water depth. By changing the equations and parameters of the velocity distribution expression, different types of waves can be generated, such as solitary waves, nonlinear waves, etc.

[0055] Furthermore, the wave generation zone can adopt an active wave absorption technology to cancel the influence of the reflected wave by generating waves opposite to the reflected wave through the wave-making boundary.

[0056] In a further technical solution, two sets of coordinate systems are established in the water entry analysis model of this embodiment, namely the world coordinate system O-XYZ, which is placed at the bottom position of the calculation area and is used to describe the motion displacement of the cylinder. The other body coordinate system O-xyz moves with the cylinder and is placed at the center position of the object surface. If it is a cylindrical object, it is placed at the center of the circular surface of the cylinder. The corresponding coordinate axes of the two coordinates are parallel to each other in the initial stage. The x-axis is parallel to the still water surface, the z-axis is vertically upward, and the y-axis is in the direction of the width side of the numerical wave pool.

[0057] In step 2, the water-entry analysis model is meshed according to the preset grid parameters to form a water-entry analysis simulation environment;

[0058] Optionally, the overlapping grid is used for meshing to handle the cylindrical motion as a moving grid. The overlapping grid is divided into a background grid and a sub-grid.

[0059] The computational domain is discretized by hexahedral meshes. The background grid is refined at the free surface and the cylindrical water-entry region to ensure the accuracy of the calculation.

[0060] As Figure 3 shown. The sub-grid is used to generate the cylinder and moves with the cylinder.

[0061] The grid distribution of the sub-grid is very important for the calculation accuracy of the free surface of the cylindrical water entry. Optionally, for the grid setting on the object surface, i.e., the cylindrical surface, specifically, a set number of o-type grids can be generated on the surface of the cylindrical object model, and then square grids are generated in the outer layer. This structure of the sub-grid can better handle the distribution of the cylindrical free surface.

[0062] Furthermore, the density of the contact area between the o-type grid and the outer square grid of the sub-grid is close, that is, it cannot exceed the set density difference, so as to improve the calculation accuracy of the free surface.

[0063] In this embodiment, the distribution of the sub-grid and the calculation results of the free surface are shown in Figure 4. It can be seen that this grid distribution can accurately handle the free surface distribution during the cylindrical water entry.

[0064] In step 3, the rigid body motion solver constrains the update of velocity and displacement, and the update control of velocity and displacement is carried out respectively according to the process of the crane ship fixing the object in the air, descending at a constant speed, and freely falling through the splash zone.

[0065] In this embodiment, a new rigid body motion solver is proposed in the water-entry analysis model for simulating the process of the crane ship lifting and lowering an object into the wave. The update of velocity and displacement is controlled by setting a constraint as follows:

[0066] (1) During the process of the object remaining stationary in the air, the motion solver does not update the displacement and velocity information of the object, simulating the preparation process of the deep-sea crane lifting the load from the deck and preparing to lower it into the sea water. The objects mentioned in this embodiment are all object models in the simulation environment.

[0067] (2) During the process of the cylindrical object falling uniformly in the air, the solver only updates the displacement information and does not update the velocity information, simulating the process of the crane ship lifting and lowering an object or load at a certain speed in the air.

[0068] (3) When the cylinder touches the free surface of the wave, the solver starts to update the cylinder velocity through the forces acting on the cylinder, approximately simulating the process that after the load touches the wave and is subjected to a large hydrodynamic impact, the cable becomes slack and thus does not constrain the load, and the load starts to free-fall into the water.

[0069] Optionally, in this embodiment, the object motion solver can be improved based on the built-in solver of OpenFOAM. First, the linear acceleration a and the angular acceleration θ are solved based on the conservation of linear momentum and the conservation of angular momentum:

[0070] a = F / m (1)

[0071] θ = I -1 ·M (2)

[0072] Where F and M are the resultant force and moment acting on the object respectively. m is the mass of the object, and I is the moment of inertia of the object. The calculation formulas for the force and moment are:

[0073] F = ∫∫ S (pE + τ)·dS + F mooring + mg (3)

[0074] M = ∫∫ S r CS ×(pE + τ)·dS + r CM ×F mooring + r CG ×mg (4)

[0075] Where E is the identity matrix, τ is the viscous stress, and S is the surface of the object. F mooring is the mooring force, r represents the moment arm, and the subscripts CS, CM, and CG represent hydrodynamic force, mooring force, and gravity respectively.

[0076] The Newmark method is used to obtain the object velocity, position, and rotation direction. Taking the linear velocity and position update as an example:

[0077]

[0078]

[0079] Δt is the time step, and γ and β are the parameters of the difference scheme. The superscript k in the above table represents the iteration number of the inner loop. C is the constraint, which is used to limit the update of velocity and displacement.

[0080] In this embodiment, a time-varying constraint tensor is set, which restricts the update of velocity or displacement in a certain direction when the object updates acceleration and displacement.

[0081] It is achievable that an interface is set up for the constraint tensor in the dynamicMeshDict file, and the value of the constraint tensor or the conversion time of the tensor can be modified before the start of the simulation or during the simulation calculation process.

[0082] During the wave generation stage, the constraint restricts the update of displacement and velocity, keeping the object stationary and waiting for the waves to form. This is also the process of simulating a crane lifting a load and suspending it in the air. Then, the constraint no longer restricts the update of the object's displacement, allowing the object to move uniformly at an initial velocity. This stage simulates the process of the crane lowering and lifting the load uniformly in the air. If the entry velocity is too fast, after the object touches the water surface, the object is affected by hydrodynamic forces, causing the cable to slacken. This part can be approximately regarded as a free-fall motion. Therefore, the constraint no longer restricts the update of the object's velocity in this part, and the object starts to move freely.

[0083] In this embodiment, a constraint is set, making the simulation process closer to the actual situation and enabling more accurate simulation results to be obtained.

[0084] In step 3, during the specific simulation process, hydrodynamic parameters are used to generate the required waves during the simulation. The object's lifting and lowering trajectory can be obtained by setting multiple object motion constraints (including velocity constraints and displacement constraints) in the configuration file to constrain or force the object's motion, and setting the duration of each constraint.

[0085] Optionally, by analyzing the object's entry process with a solver, the data of the object entering the waves can be obtained by solving the force data of entering the waves at different wave positions.

[0086] Specifically, for the process of the object entering the waves at each different wave position, the data of the object's waves can be solved, which can be solved separately in stages, including the impact stage, the jet generation stage, the cavity closure stage, and the immersion stage.

[0087] Specifically, the data of the cylindrical object entering the waves includes the variation of the vertical force and horizontal force with time, the pressure distribution on the surface of the cylindrical object, and the distribution of the free liquid surface.

[0088] The specific simulation experiment process of this embodiment is as follows:

[0089] Taking a cylinder with a radius of 0.1 m and a length of 1 m as an example, the data of the cylinder entering the waves is calculated, including the variation of hydrodynamic forces, the distribution of the free liquid surface, and the pressure distribution, etc. The cylinder waits for the waves to form in the air. Then, the cylinder descends uniformly at a speed of 1 m / s until the surface of the cylinder touches the free surface of the waves and enters the water in a free-fall motion with an entry velocity of 1 m / s.

[0090] 1) Analysis of the cylinder entering the waves at the wave crest

[0091] The force variation of the cylinder during the water entry stage is shown in Figure 5. The water entry stage of the cylinder is divided into four stages: the impact stage, the jet generation stage, the cavity closure stage, and the immersion stage. It can be seen that at the initial stage of impact, the cylinder is subjected to a large hydrodynamic impact, and then the hydrodynamic force rapidly decreases, while the horizontal force increases with time. In the jet generation stage, the vertical force on the cylinder increases again, while the horizontal force begins to decrease. In the cavity closure stage, since the liquid above the cylinder compresses the air in the cavity, a great pressure impact is exerted on the upper part of the cylinder, resulting in a rapid decrease in the force on the cylinder and an increase in the negative direction, which means that the cylinder is subjected to a large downward force. This downward and suddenly increasing force will cause the cable to be suddenly tightened, increasing the risk of cable breakage. In the immersion stage, the vertical force on the cylinder gradually stabilizes while the horizontal force slowly increases.

[0092] Figure 6 Figure 6 shows the free surface distribution of the cylinder entering the wave in four stages. It can be seen that the mesh used in this model can accurately solve the free surface distribution, including the formation of slender jets and cavities.

[0093] The pressure distribution on the surface of the cylinder is as Figure 7 shown. In the impact stage, the pressure peak appears on both sides of the cylinder, and as the water entry time increases, the pressure gradually decreases, which is consistent with the change of the vertical force of the cylinder in the impact stage. In the jet generation stage, the maximum pressure gradually moves towards the center of the cylinder surface, and the pressure increases with the increase of the water entry time. In the cavity closure stage, the air in the cavity is squeezed by the liquid on both sides, causing a sharp increase in pressure on the upper surface of the cylinder. This pressure quickly decreases as the air leaves the upper surface of the cylinder. In the immersion stage, the pressures on the upper and lower surfaces of the cylinder both increase slowly.

[0094] 2) Analysis of the cylinder entering the water at different wave positions

[0095] Four positions of the wave are selected for the water entry simulation, namely the wave crest, the wave trough, the ascending point, and the descending point. These four positions are as Figure 8 shown.

[0096] By adjusting the time parameter of the constraint of the proposed rigid body motion solver, the position of the cylinder entering the wave is adjusted. The force data of the cylinder entering the water at the four positions of the wave with an entry speed of 1 m / s are shown in Figure 9. It can be seen that in the impact stage, the vertical force of the cylinder entering the water at the descending point is the largest, and the vertical force at the ascending point is the smallest. The directions and change trends of the horizontal forces on the cylinder at the wave crest and the wave trough are just opposite. In the cavity closure stage, the downward hydrodynamic forces on the cylinder at the wave crest and the wave trough are the largest, and the cavity of the cylinder entering the water at the wave trough closes earlier, while the cavity of the cylinder entering the water at the wave crest closes the latest.

[0097] Example 2

[0098] Based on Example 1, this embodiment provides a simulation system for simulating a crane vessel lifting an object into water, comprising:

[0099] A construction module is configured to construct a water entry analysis model including a water pool model and an object model according to the acquired water pool parameters and object parameters;

[0100] A grid division module is configured to perform grid division on the water entry analysis model according to preset grid parameters to form a water entry analysis simulation environment;

[0101] The simulation execution module is configured to simulate the falling of the object model in the water pool model according to the obtained simulation environment parameters and the object lifting trajectory in the simulation environment, and to simulate the process of the crane vessel lifting the object into the water by updating the velocity and displacement constraints of the rigid body motion solver to obtain the free surface distribution and pressure distribution of the object entering the water.

[0102] Example 3

[0103] This embodiment provides an electronic device, including a memory and a processor, and computer instructions stored in the memory and running on the processor. When the computer instructions are run by the processor, the steps described in the method of Embodiment 1 are completed.

[0104] Example 4

[0105] This embodiment provides a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the steps described in the method of Embodiment 1 are completed.

[0106] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

[0107] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A simulation method for simulating the lowering of an object into water by a crane vessel, characterized in that It includes the following steps: According to the obtained pool parameters and object parameters, an entry analysis model including a pool model and an object model is constructed; in the entry analysis model, two sets of coordinate systems are established, namely the world coordinate system O-XYZ, which is placed at the bottom position of the calculation area and is used to describe the movement displacement of the cylinder; the other body coordinate system O-xyz follows the movement of the cylinder and is placed at the center position of the object surface. The corresponding coordinate axes of the two coordinates are parallel to each other in the initial stage. The x-axis is parallel to the still water surface, the z-axis is vertically upward, and the y-axis is in the direction of the width side of the numerical wave pool; According to the preset grid parameters, the entry analysis model is meshed to form an entry analysis simulation environment; a set number of o-type grids are generated on the surface of the object model, and then square grids are generated on the outer layer; In the simulation environment, according to the obtained simulation environment parameters and the object hoisting trajectory, the object model is simulated to fall in the pool model. The update of the speed and displacement is constrained by the rigid body motion solver, and the process of the crane ship hoisting the object into the water is simulated to obtain the free surface distribution and pressure distribution during entry; The rigid body motion solver obtains the object speed, position and rotation direction according to the linear conservation and angular momentum conservation, and adopts the Newmark method to obtain the free surface distribution and pressure distribution during entry; the rigid body motion solver constrains the update of the speed and displacement, and the specific constraints are as follows: during the process of the object remaining stationary in the air, the motion solver does not update the object displacement and speed information; during the process of the object falling uniformly in the air, the solver only updates the displacement information and does not update the speed information; when the cylinder touches the free liquid surface of the wave, the solver starts to update the cylinder speed through the force on the cylinder.

2. The simulation method for simulating the hoisting and lowering of an object into water by a crane ship according to claim 1, characterized in that: The pool model is partitioned, including a wave generation area and an impact area. The wave generation area is configured to generate simulated waves, and the impact area is the area where the object model enters the water.

3. The simulation method for simulating the hoisting and lowering of an object into water by a crane vessel according to claim 2, characterized in that: A wave-making boundary is set on the side of the wave generation area relative to the impact area; Alternatively, the wave generation area adopts an active wave absorption method, and waves opposite to the reflected waves are generated through the wave-making boundary to offset the influence of the reflected waves; Alternatively, two sets of coordinate systems are established in the entry analysis model, namely the world coordinate system and the body coordinate system. The world coordinate system is placed at the bottom position of the pool model and is used to describe the movement displacement of the object; the other body coordinate system follows the movement of the object entering the water and is placed at the center position of the object surface.

4. A simulation method for simulating the hoisting and lowering of an object into water by a crane ship as described in claim 1, characterized in that: The rigid body motion solver constrains the update of the speed and displacement, and the speed and displacement update control are carried out respectively according to the process of the crane ship fixing the object in the air, descending uniformly and freely falling through the splash zone.

5. The simulation method for simulating the hoisting and lowering of an object into water by a crane ship according to claim 1, wherein: Through the analysis of the object entry process by the solver, the data of the object entering the wave are obtained by solving and analyzing the force data of entering the water at different wave positions.

6. A simulation system for simulating the hoisting and lowering of an object into water by a crane vessel, characterized in that, It includes: A construction module, configured to construct an entry analysis model including a pool model and an object model according to the obtained pool parameters and object parameters; In the water entry analysis model, two sets of coordinate systems are established. One is the world coordinate system O-XYZ, which is placed at the bottom of the calculation area and used to describe the movement displacement of the cylinder. The other is the body coordinate system O-xyz, which moves with the cylinder and is placed at the center of the object surface. The corresponding coordinate axes of the two coordinates are parallel to each other in the initial stage. The x-axis is parallel to the still water surface, the z-axis is vertically upward, and the y-axis is in the direction of the width side of the numerical wave tank. The mesh generation module is configured to mesh the water entry analysis model according to preset mesh parameters to form a water entry analysis simulation environment. A set number of o-type meshes are generated on the surface of the object model, and then square meshes are generated in the outer layer. The simulation execution module is configured to, in the simulation environment, simulate the object model falling in the pool model according to the obtained simulation environment parameters and the object lifting trajectory, and constrain the update of velocity and displacement through a rigid body motion solver, so as to simulate the process of the lifting ship lifting and dropping the object into the water, and obtain the free surface distribution and pressure distribution of the water entry. The rigid body motion solver obtains the object velocity, position and rotation direction according to the linear conservation and angular momentum conservation, and adopts the Newmark method to obtain the free surface distribution and pressure distribution of the water entry. The rigid body motion solver constrains the update of velocity and displacement. The specific constraints are as follows: During the process when the object remains stationary in the air, the motion solver does not update the object displacement and velocity information; During the process when the object falls uniformly in the air, the solver only updates the displacement information and does not update the velocity information; When the cylinder touches the free liquid surface of the wave, the solver starts to update the cylinder velocity through the force on the cylinder.

7. An electronic device, characterized in that, It includes a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the steps of the method according to any one of claims 1-5 are completed.

8. A computer-readable storage medium, characterized in that, It is used to store computer instructions, and when the computer instructions are executed by the processor, the steps of the method according to any one of claims 1-5 are completed.

Images