Wave train reproduction method based on SPH numerical pool

Abstract

The technical scheme is combined with an improved time reversal method to provide a wave train reproduction method based on an SPH numerical pool, the numerical wave pool based on the SPH method is constructed, the target wave train is subjected to time reversal and then is subjected to fast Fourier transform to obtain a first-time wave generation signal, the first-time wave generation signal is used for generating waves in the numerical pool, and the first-time wave generation signal and the second-time wave generation signal are used for generating waves in the numerical pool. The method comprises the following steps: recording at a specified position of a numerical pool to obtain a wave time calendar of first-time wave generation, carrying out time reversal on the wave time calendar recorded at the specified position of the numerical pool after the first-time wave generation, generating a second-time wave generation signal by using a reversed wave train, and introducing the second-time wave generation signal into the numerical pool to carry out second-time wave generation, the reproduced target wave train is recorded at the specified position of the numerical pool, the problem that the wave phase and amplitude cannot be accurately controlled when the SPH method is used for simulating the wave train is solved, and accurate simulation of the deterministic wave train can be achieved.

Description

Technical Field

[0001] This invention relates to a numerical wave train simulation method in a water tank based on the Smooth Particle Hydrodynamics (SPH) method, which is particularly suitable for timed and fixed-point simulation of target wave trains containing extreme waves, and belongs to the fields of computational fluid dynamics and marine engineering. Background Technology

[0002] In the field of naval architecture and ocean engineering, the simulation of deterministic wave trains is of great significance for studying the interaction between waves and structures. Traditional physical pool tests suffer from drawbacks such as high cost and low accuracy when simulating extreme waves. Among numerical simulation methods, potential flow theory-based methods struggle to handle nonlinear phenomena such as wave breaking, while traditional CFD methods suffer from mesh distortion and other problems when simulating extreme waves. The SPH method, as a meshless Lagrangian method, has unique advantages in handling large deformations of free surfaces. However, existing SPH wave simulation methods are insufficient in accurately controlling wave phase and amplitude, making it difficult to accurately simulate deterministic wave trains. Especially when simulating target wave trains containing extreme waves, the accurate simulation of phase and amplitude directly affects the reliability of the simulation results. Summary of the Invention

[0003] The purpose of this invention is to propose a method for simulating a target wave train based on an SPH numerical water tank and combined with an improved time reversal technique. By precisely controlling the phase and amplitude of each component wave in the wave train, the method can accurately simulate a target wave train containing extreme waves.

[0004] To achieve the above objectives, the technical solution of this invention discloses a wave train reproduction method based on an SPH numerical water tank, characterized by comprising the following steps: Step 1: Construct a numerical pool model using the SPH method; Step 2: Reverse the time of the target wave train, use the reversed target wave train to generate the first wave signal, and import the first wave signal into the numerical pool model to generate the first wave. Step 3: Record the wave history of the first wave generation at a specified location in the numerical water tank model. Reverse the wave history recorded at the specified location in the numerical water tank model after the first wave generation, and use the reversed wave train to generate the second wave generation signal. Step 4: Import the second wave signal into the numerical water tank model to generate a second wave, and record the reproduced target wave train at the specified position in the numerical water tank model.

[0005] Preferably, the numerical water tank model constructed in step 1 includes a wave-generating section, a working section, and a wave-dissipating section, and a particle-filled domain is arranged in the working section.

[0006] Preferably, in step 1, a precisely controllable pusher-type wave generator is installed in the numerical water tank model.

[0007] Preferably, in step 1, the wave-dissipating section of the numerical water tank model is a damping wave-dissipating method; the wave-generating plate of the pusher-type wave generator moves according to the position-time curve, and the water particle spacing, simulation time, time step coefficient, water density, gravitational acceleration, and viscosity coefficient are set.

[0008] Preferably, in step 2, the first wave signal is generated using the following method: The target wave list is The target wave train is time-reversed to Where S is the time length of the target wave train, T indicates that the wave train is the target wave train, and R indicates that the wave train is time-reversed; right Perform a fast Fourier transform to obtain the frequencies of its constituent waves. ,amplitude and phase , where n is the component wave index; Hydraulic transfer function of wave-making plate The first wave signal was obtained. In the formula, where h is the frequency and h is the water depth. Let N be the wave number, and N be the number of constituent waves.

[0009] Preferably, in step 2, a command to read the wave-generating plate motion signal is written into the numerical calculation file to start the numerical simulation calculation.

[0010] Preferably, in step 3, the calculation results obtained from the numerical simulation are post-processed to obtain the wave duration measured at a specified location during the first wave generation in the numerical water tank. .

[0011] Preferably, in step 3, the second wave signal is generated using the following method: The wave time history at the specified location obtained from the first wave generation simulation. Reverse time to obtain ; right The frequency of its constituent waves is obtained by performing a fast Fourier transform. and phase Combined with the target wave train Reversed wave train The component wave amplitude obtained by performing a fast Fourier transform ; Using the hydraulic transfer function of the push plate The second wave signal was calculated. .

[0012] Preferably, in step 3, a command to read the wave-generating plate motion signal is written into the numerical calculation file to start the numerical simulation calculation.

[0013] Preferably, in step 4, the calculation results of the numerical simulation in step 3 are post-processed to obtain the target wave train reproduced at the specified location.

[0014] This invention proposes a wave train reconstruction method based on the SPH numerical wave tank. It constructs a numerical wave tank based on the SPH method, reverses the time of the target wave train, and performs a Fast Fourier Transform to obtain the first wave generation signal. This first wave generation signal is used to generate waves in the numerical tank, and the wave history of the first wave generation is recorded at a designated location in the numerical tank. The wave history recorded at the designated location in the numerical tank during the first wave generation is then reversed, and the reversed wave train is used to generate a second wave generation signal. This second wave generation signal is then imported into the numerical tank for a second wave generation, and the reconstructed target wave train is recorded at a designated location in the numerical tank. This method solves the problem of inaccurate control of wave phase and amplitude when simulating wave trains using the SPH method, and enables accurate simulation of deterministic wave trains. Attached Figure Description

[0015] Figure 1 A flowchart of a wave train reproduction method based on an SPH numerical water tank provided for an embodiment of the present invention; Figure 2 A schematic diagram of a numerical water tank provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the target wave train and its time reversal provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the first wave generation signal provided in an embodiment of the present invention; Figure 5 The wavefront time history and its time reversal diagram of the target position recorded in the first wave generation provided in this embodiment of the invention; Figure 6 This is a schematic diagram of the second wave generation signal provided in an embodiment of the present invention; Figure 7 This is a schematic diagram comparing the wave train obtained from the second wave generation signal simulation with the target wave train, provided in an embodiment of the present invention. Detailed Implementation

[0016] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0017] like Figure 1 As shown in the example, this invention provides a wave train reconstruction method based on the SPH numerical water tank, suitable for the numerical reconstruction of deterministic wave trains. It can effectively obtain the wave phase and amplitude when simulating deterministic wave trains using the SPH method, achieving accurate simulation of deterministic wave trains. Combined with... Figure 1 Specifically, it includes the following steps.

[0018] Step 1: Construct a numerical wave pool based on the SPH method using the open-source software DualSPHysics, such as... Figure 2 As shown, the constructed numerical wave pool is a three-section structure, including a wave-generating section, a working section, and a wave-dissipating section. The numerical wave pool is equipped with a precisely controllable pusher-type wave generator, and the working section of the numerical wave pool is arranged with a particle-filled domain.

[0019] In a preferred embodiment of the present invention, the wave-damping section of the numerical wave pool employs a damping wave-damping method. The wave-generating plate of the push-plate wave generator moves according to the position-time curve. The water particle spacing is set to 0.005, the simulation time to 50s, the time step coefficient to 0.05, and the water density to 1.0g / cm³. 3 Gravitational acceleration: 9.81 m / s² 2 Parameters such as these.

[0020] Step 2: Reverse the time of the target wave train and use the reversed target wave train to generate the first wave generation signal. Import the first wave generation signal into the numerical wave pool to generate the first wave.

[0021] In a preferred embodiment of the present invention, the first wave signal is generated by the following steps: The target wave list is The target wave train is time-reversed to Where S is the time length of the target wave train, T indicates that the wave train is the target wave train, and R indicates that the wave train is time-reversed; right Perform a fast Fourier transform to obtain the frequencies of its constituent waves. ,amplitude and phase n is the component wave number; Hydraulic transfer function of wave-making plate The first wave signal was obtained. In the formula, where h is the frequency and h is the water depth. Let N be the wave number, and N be the number of constituent waves.

[0022] Write the command to read the first wave-generating plate motion signal into the numerical calculation file to start the numerical simulation calculation.

[0023] For example, such as Figure 3 As shown, time reversal is performed based on the target wave train to obtain the time-reversed wave train of the target wave train. Figure 4 The motion history of the wave-pushing plate during the first wave generation is given.

[0024] Step 3: Record the wave history of the first wave generation at a designated location in the numerical wave pool. Reverse the wave history recorded at the designated location in the numerical wave pool during the first wave generation, and use the reversed wave train to generate the second wave generation signal.

[0025] In a preferred embodiment of the present invention, the second wave signal is generated by the following steps: The calculation results are post-processed to obtain the wave duration measured at a specified location during the first wave generation in the numerical water tank. ; The wave time history at the specified location obtained from the first wave generation simulation. Reverse time to obtain ,right The frequency of its constituent waves is obtained by performing a fast Fourier transform. and phase Combined with the target wave train Reversed wave train The component wave amplitude obtained by performing a fast Fourier transform Using the hydraulic transfer function of the push plate The second wave signal was calculated. .

[0026] For example, by generating waves for the first time, we can obtain... Figure 5 The wave time history at the location x=6m shown, and the time reversal of that time history. Further, the following is obtained: Figure 6 The motion time of the wave-pushing plate during the second wave generation is shown.

[0027] Step 4: Import the second wave generation signal into the numerical wave tank for a second wave generation. Record the reproduced target wave train at the designated location in the numerical wave tank.

[0028] In a preferred embodiment of the invention, a command to read the motion signal of the second wave-generating plate is written into the numerical calculation file to initiate numerical simulation. The calculation results are then post-processed to obtain the target wave train reproduced at the specified location.

[0029] For example, a second wave can be generated to obtain... Figure 7 The simulated wave train at position x=6m in the numerical water tank is shown, and its comparison with the target wave train is shown.

[0030] The wave train reproduction method based on the SPH numerical water tank described above can obtain the amplitude and phase of the component waves of the reproduced deterministic wave train and can be applied to the accurate reproduction of various deterministic wave trains.

[0031] The description and accompanying drawings provide typical embodiments of specific structures for specific implementations. Other modifications are possible based on the spirit of the invention. While the above-described invention presents preferred embodiments, these are not intended to be limiting. Various changes and modifications will undoubtedly become apparent to those skilled in the art after reading the above description. Therefore, the appended claims should be considered to cover all changes and modifications that encompass the true intent and scope of the invention. Any and all equivalent scope and content within the scope of the claims should be considered to still fall within the intent and scope of the invention.

Claims

1. A wave train reproduction method based on a SPH numerical water tank, characterized in that, Includes the following steps: Step 1: Construct a numerical pool model using the SPH method; Step 2: Reverse the time of the target wave train, generate the first wave signal using the reversed target wave train, and import the first wave signal into the numerical pool model for the first wave generation; Step 3: Record the wave history of the first wave generation at a specified location in the numerical pool model, reverse the time of the wave history recorded at the specified location in the numerical pool model after the first wave generation, and generate the second wave signal using the reversed wave train; Step 4: Import the second wave signal into the numerical pool model for the second wave generation, and record the reproduced target wave train at a specified location in the numerical pool model.

2. The wave train reproduction method based on a numerical hydrograph (SPH) pool as described in claim 1, characterized in that, The numerical water tank model constructed in step 1 includes a wave-generating section, a working section, and a wave-dissipating section, with a particle-filled domain arranged in the working section.

3. The wave train reproduction method based on a numerical water tank with SPH as described in claim 2, characterized in that, In step 1, a precisely controllable pusher-type wave generator is installed in the numerical water tank model.

4. The wave train reproduction method based on a numerical water tank with SPH as described in claim 3, characterized in that, In step 1, the wave-dissipating section of the numerical water tank model is a damping wave-dissipating method; the wave-generating plate of the pusher-type wave generator moves according to the position-time curve, and the water particle spacing, simulation time, time step coefficient, water density, gravitational acceleration, and viscosity coefficient are set.

5. The wave train reproduction method based on a numerical water tank with SPH as described in claim 4, characterized in that, In step 2, the first wave generation signal is generated using the following method: the target wave list is made as follows: The target wave train is time-reversed to Where S is the time length of the target wave train, T indicates that the wave train is the target wave train, and R indicates time reversal of the wave train; for Perform a fast Fourier transform to obtain the frequencies of its constituent waves. ,amplitude and phase n is the wave index; the hydraulic transfer function of the wave-generating plate is used. The first wave signal was obtained. In the formula, where h is the frequency and h is the water depth. Let N be the wave number, and N be the number of constituent waves.

6. The wave train reproduction method based on an SPH numerical water tank as described in claim 5, characterized in that, In step 2, a command to read the wave-generating plate motion signal is written into the numerical calculation file to start the numerical simulation calculation.

7. The wave train reproduction method based on a SPH numerical water tank as described in claim 6, characterized in that, In step 3, the calculation results obtained from the numerical simulation are post-processed to obtain the wave time history measured at a specified location during the first wave generation in the numerical water tank. .

8. The wave train reproduction method based on a numerical water tank with SPH as described in claim 7, characterized in that, In step 3, the second wave generation signal is generated using the following method: the wave time history at the specified location obtained from the first wave generation simulation is used. Reverse time to obtain ;right The frequency of its constituent waves is obtained by performing a fast Fourier transform. and phase Combined with the target wave train Reversed wave train The component wave amplitude obtained by performing a fast Fourier transform ; Using the hydraulic transfer function of the push plate The second wave signal was calculated. .

9. The wave train reproduction method based on a numerical water tank with SPH as described in claim 8, characterized in that, In step 3, a command to read the wave-generating plate motion signal is written into the numerical calculation file to start the numerical simulation calculation.

10. The wave train reproduction method based on an SPH numerical water tank as described in claim 9, characterized in that, In step 4, the calculation results of the numerical simulation in step 3 are post-processed to obtain the target wave train reproduced at the specified location.

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