Simulation method and system for sediment scouring and deposition of port pile foundation terminals based on FVCOM-SWAVE and OpenFOAM

Abstract

The present invention discloses a method and system for simulating sediment scouring and deposition of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM. The method and system include: establishing an FVCOM-SWAVE model according to the sea area where the port pile foundation terminal is located, and establishing multiple OpenFOAM models in combination with the calculation area of ​​the FVCOM-SWAVE model based on the measured sediment scouring and deposition morphology data of the pile foundation terminal; transferring the wave-current coupling calculation data at the boundary of the FVCOM-SWAVE model to the OpenFOAM model as initial values ​​and verification values, carrying out numerical experiments on the pile foundation water blocking effect and sediment scouring and deposition based on the OpenFOAM model, and obtaining simulation results of the interaction between waves, currents, sediment and the port pile foundation terminal through calculation; dynamically exchanging the boundary conditions calculated by the FVCOM-SWAVE model and the three-dimensional port pile foundation terminal sediment scouring and deposition information simulated by the OpenFOAM model to produce a terrain file and a bottom friction coefficient file, and comparing them with the simulation results at the previous time, and using the difference in the hydrodynamic environment simulated by the two as a basis for judging the impact of changes in the water and sediment environment around the piles.

Description

Technical Field

[0001] The present invention relates to the technical field of port pile foundation wharf sediment deposition analysis, and in particular to a port pile foundation wharf sediment scouring and deposition simulation method and system based on FVCOM-SWAVE and OpenFOAM. Background Art

[0002] Pile-foundation port terminals are a common type of port terminal. Due to their unique location, they are directly affected by waves, currents, and sediment, often resulting in a complex and dynamic marine environment. Furthermore, the piles themselves can influence nearshore dynamic conditions such as waves, currents, and sediment. Furthermore, significant sediment accumulation often occurs near the pile foundations. Therefore, consideration should be given to the effects of wave and current forces in the waters surrounding pile-foundation port terminals, as well as the movement of sediment around the pile foundations and the changes in sediment erosion and deposition.

[0003] Currently used numerical simulation technologies often have a single scale, either describing the mesoscale ocean dynamics or the small-scale sediment accumulation in the waters where port pile-foundation terminals are located. For example, using the FVCOM-SWAVE model alone for numerical simulation can calculate mesoscale background flows with good results, but it cannot accurately simulate the subtle flow conditions caused by tidal currents and waves acting on pile foundations, nor can it provide a detailed description of sediment accumulation in pile foundations. Using the OpenFOAM model alone for numerical simulation can accurately simulate the subtle flow conditions caused by tidal currents and waves acting on pile foundations and provide a detailed description of sediment accumulation in pile foundations, with high computational accuracy, but it cannot quickly simulate the effects of mesoscale background flows on sediment and pile foundations.

[0004] Therefore, a port pile foundation terminal sediment scouring and siltation simulation method and system based on FVCOM-SWAVE and OpenFOAM is provided, which can accurately and quickly perform comprehensive simulation calculations of sediment scouring and siltation. Summary of the Invention

[0005] Therefore, in order to solve the above defects in the prior art, the present invention provides a simulation method for sediment scouring and deposition of port pile foundation terminals based on FVCOM-SWAVE and OpenFOAM, which accurately evaluates and predicts the sediment scouring and deposition process of port pile foundation terminals through the calculation method of spatiotemporal variation bottom friction coefficient through small-scale numerical model inversion.

[0006] The present invention discloses a method for simulating sediment scouring and silting of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM, comprising the following steps:

[0007] S1. Establish an FVCOM-SWAVE model based on the sea area where the port's pile-foundation wharf is located. Based on the measured data on the sediment erosion and deposition patterns of the pile-foundation wharf, multiple OpenFOAM models are established in the FVCOM-SWAVE model calculation area. The FVCOM-SWAVE and OpenFOAM model grids are processed using the overlaid mesh method, with arbitrary overlap between the model grids.

[0008] S2. Simulate and calculate three-dimensional layered wave-current coupling data based on the FVCOM-SWAVE model. Output parameters include tide level, wave height, wave period, current velocity, and current direction. The initial bottom friction coefficient is the recommended constant for the sea area. The FVCOM-SWAVE model simulation results are repeatedly calibrated until the simulated value no longer changes.

[0009] S3. Using a three-dimensional numerical interpolation method, the wave-current coupling data calculated by the FVCOM-SWAVE model are interpolated to the grid nodes of the OpenFOAM model;

[0010] S4. Transfer the wave-current coupling calculation data (i.e., the interpolated data in S3) at the boundary of the FVCOM-SWAVE model to the OpenFOAM model as the initial and verification values. Conduct numerical experiments on the water-blocking effect of pile foundations and sediment scouring and deposition based on the OpenFOAM model. Simulate the interaction between waves, currents, sediment, and the port pile foundation terminal through calculations.

[0011] S5: Analyze the sediment erosion and deposition patterns around the pile calculated by the OpenFOAM model to obtain the current terrain information and bottom friction parameter information around the pile. Import the terrain information into the terrain file of the FVCOM-SWAVE model to update it. Create a bottom friction parameter file suitable for the current sea area as the startup file of the FVCOM-SWAVE model to simulate the dynamic waves and flow conditions around the sediment erosion and deposition pile.

[0012] S6: Dynamically exchange the boundary conditions calculated by the FVCOM-SWAVE model with the terrain file and bottom friction coefficient file generated by the OpenFOAM model's simulated three-dimensional port pile foundation terminal sediment scouring and deposition information, and compare them with the simulation results at the previous time. The difference in the simulated hydrodynamic environment between the two is used as the basis for judging the impact of changes in the water and sediment environment around the piles.

[0013] The FVCOM-SWAVE model simulates and calculates the mesoscale wave-current coupling in the sea area where the pile foundation is located. The calculated data include tide level, flow velocity, flow direction, wave height, and wave period. The OpenFOAM model simulates and calculates the small-scale sediment scouring and deposition data in the sea area where the pile foundation is located. The calculated data include the terrain parameters and bottom friction coefficient after sediment scouring and deposition.

[0014] The numerical simulation calculation process of the OpenFOAM model includes hydrodynamic calculations; specifically, by calculating the RANS equations and turbulent closed equations, using the Waves2FOAM tool developed based on the interFoam solver in OpenFOAM to generate waves, solve the OpenFOAM hydrodynamic model, and use the VOF method to couple the free water surface simulation to capture the propagation and deformation of waves around the pile foundation and various bottom friction parameter points to obtain the flow velocity, flow direction and free water surface elevation. Among them, the flow velocity and free water surface elevation are compared and verified with the tide level and flow velocity in the results transmitted by FVCOM-SWAVE.

[0015] The numerical simulation process of the OpenFOAM model also includes sediment calculations. Specifically, the OpenFOAM sediment transport model is solved by calculating the bedload and suspended load sediment transport equations. The initial data comes from the OpenFOAM hydrodynamic model calculation results, and the calculation results, including the sediment transport rate, are obtained.

[0016] The numerical simulation calculation process of the OpenFOAM model also includes the calculation of bed deformation. Specifically, the OpenFOAM bed deformation model is solved by solving the sediment continuity equation. The initial data comes from the calculation results of the OpenFOAM sediment transport model. The deformation of the bed around the pile foundation is solved. The convergence condition of the OpenFOAM numerical simulation is set to <10 -6 , and scan the bed surface to obtain the sediment scouring and siltation situation around the port pile foundation terminal and at each bottom friction parameter point.

[0017] The selection points of multiple independent bottom friction coefficients are determined according to the seabed topography. One point is selected every 1000m in the calculation sea area as an independent bottom friction coefficient, and the arrangement form is a plum blossom shape.

[0018] The mesh resolution of the FVCOM-SWAVE model in the overlapping area is 1-1.5 times that of the OpenFOAM model in the overlapping area.

[0019] The mesh resolution of the OpenFOAM model in the overlapping area ranges from 10m to 50m, and the mesh resolution of the OpenFOAM model in the non-overlapping area ranges from 0.1m to 10m.

[0020] The grid resolution of the FVCOM-SWAVE model in the overlapping area ranges from 5m to 75m, and the grid resolution of the FVCOM-SWAVE model in the non-overlapping area ranges from 75m to 300m.

[0021] Furthermore, the present invention also provides a port pile foundation terminal sediment scouring and silting simulation system based on FVCOM-SWAVE and OpenFOAM, which uses the simulation method described above to perform simulation calculation / analysis.

[0022] The technical solution of the present invention has the following advantages:

[0023] In the present invention, a joint simulation method that comprehensively considers mesoscale background flow and small-scale sediment deposition is established, which solves the joint simulation problem of the interaction between mesoscale wave-current coupling data and small-scale port pile foundation terminal and sediment, thereby obtaining multi-scale physical phenomena, such as the mutual influence of mesoscale wave-current coupling and dynamic terrain and dynamic bottom friction coefficient, and the sediment scouring and deposition phenomenon of small-scale port pile foundation terminal under different wave and current data; and improves the bottom friction coefficient accuracy of the mesoscale numerical model, obtains the dynamic sediment scouring and deposition model through the small-scale numerical model calculation, and inverts the bottom friction parameters according to the dynamic terrain, water level and flow velocity calculation data, so as to accurately and quickly evaluate and predict the sediment scouring and deposition process of the port pile foundation terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of the method for simulating sediment scouring and deposition of a port pile foundation terminal according to the present invention;

[0026] Figure 2 This is a schematic diagram of the overlapping grids of the inner and outer domains for calculation according to the present invention;

[0027] Figure 3 Schematic diagram of the mesoscale grid of the FVCOM-SWAVE model of the present invention;

[0028] Figure 4 A schematic diagram of a small-scale grid of the OpenFOAM model of the present invention;

[0029] Figure 5 This is a flow chart for assigning independent bottom friction coefficients according to the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Example 1: Figure 1 As shown, this embodiment provides a method for simulating sediment scouring and deposition of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM, comprising the following steps:

[0033] S1. Establish an FVCOM-SWAVE model based on the sea area where the port's pile-foundation wharf is located. Based on the measured data on the sediment erosion and deposition patterns of the pile-foundation wharf, multiple OpenFOAM models are established in the FVCOM-SWAVE model calculation area. The FVCOM-SWAVE and OpenFOAM model grids are processed using the overlaid mesh method, with arbitrary overlap between the model grids.

[0034] S2. Simulate and calculate three-dimensional layered wave-current coupling data based on the FVCOM-SWAVE model. Output parameters include tide level, wave height, wave period, current velocity, and current direction. The initial bottom friction coefficient is the recommended constant for the sea area. The FVCOM-SWAVE model simulation results are repeatedly calibrated until the simulated value no longer changes.

[0035] S3. Using a three-dimensional numerical interpolation method, the wave-current coupling data calculated by the FVCOM-SWAVE model are interpolated to the grid nodes of the OpenFOAM model;

[0036] S4. Transfer the wave-current coupling calculation data (i.e., the interpolated data in S3) at the boundary of the FVCOM-SWAVE model to the OpenFOAM model as the initial and verification values. Conduct numerical experiments on the water-blocking effect of pile foundations and sediment scouring and deposition based on the OpenFOAM model. Simulate the interaction between waves, currents, sediment, and the port pile foundation terminal through calculations.

[0037] S5: Analyze the sediment erosion and deposition patterns around the pile calculated by the OpenFOAM model to obtain the current terrain information and bottom friction parameter information around the pile. Import the terrain information into the terrain file of the FVCOM-SWAVE model to update it. Create a bottom friction parameter file suitable for the current sea area as the startup file of the FVCOM-SWAVE model to simulate the dynamic waves and flow conditions around the sediment erosion and deposition pile.

[0038] S6: Dynamically exchange the boundary conditions calculated by the FVCOM-SWAVE model with the terrain file and bottom friction coefficient file generated by the OpenFOAM model's simulated three-dimensional port pile foundation terminal sediment scouring and deposition information, and compare them with the simulation results at the previous time. The difference in the simulated hydrodynamic environment between the two is used as the basis for judging the impact of changes in the water and sediment environment around the piles.

[0039] Specifically, the FVCOM-SWAVE model simulates and calculates the mesoscale wave-current coupling in the sea area where the pile foundation is located, and the calculated data include tide level, flow velocity, flow direction, wave height, and wave period; the OpenFOAM model simulates and calculates the small-scale sediment scouring and deposition data in the sea area where the pile foundation is located, and the calculated data include the terrain parameters and bottom friction coefficient after sediment scouring and deposition.

[0040] Multiple independent bottom friction coefficient points are determined based on the seabed topography. Within the calculation area, independent bottom friction coefficient points are selected every 1000 meters, arranged in a plum blossom pattern. In this example, the first point is the location of the piled pier, and the calculation then expands outward in a plum blossom pattern from this initial point. Additional points are added in areas with significant topographical variations, such as elevation differences greater than 600 meters.

[0041] Furthermore, it is preferred that the grid resolution of the FVCOM-SWAVE model in the overlapping area is 1-1.5 times the grid resolution of the OpenFOAM model in the overlapping area; specifically, the grid resolution range of the OpenFOAM model in the overlapping area can be set to 10m-50m, and the grid resolution range of the OpenFOAM model in the non-overlapping area can be set to 0.1m-10m; at the same time, the grid resolution range of the FVCOM-SWAVE model in the overlapping area is 5m-75m, and the grid resolution range of the FVCOM-SWAVE model in the non-overlapping area is 75m-300m.

[0042] In this embodiment, based on the multi-area overlapping grid method (Chimera method), the sea area where the port pile foundation terminal is located is divided into multiple sets of overlapping sub-areas, and sub-grids suitable for the FVCOM-SWAVE model and OpenFOAM model are generated in each of the multiple sub-areas. The schematic diagram of the overlapping grid of the pile foundation calculation area is shown in the figure below. Figure 2 As shown in the figure, the subgrid of the FVCOM-SWAVE model is the outer domain of the calculation area, and the subgrid of the OpenFOAM model is the outer domain of the calculation area. During the coupled calculation of waves, currents, sediments, and pile foundations, the information such as flow velocity, flow direction, tide level, wave height, wave period, terrain, and bottom friction coefficient between the two sets of subregions is transmitted through interpolation of grid nodes in the overlapping area.

[0043] Furthermore, a two-dimensional unstructured coarse-resolution grid with a spacing between 5m and 300m is set in the outer domain of the port pile foundation terminal model through the MATLAB program, such as Figure 3As shown, the mesoscale FVCOM model simulates three-dimensional stratified tidal currents and wave motions over a large area of ​​the ocean. The FVCOM model's primitive equations are the Reynolds-averaged three-dimensional governing ocean equations, including the water continuity and momentum equations, temperature and salinity equations, and turbulence equations. The FVCOM primitive equations can be solved using either semi-implicit methods or pattern splitting. FVCOM uses an unstructured triangular grid horizontally and σ-coordinates, s-coordinates, and hybrid coordinate systems vertically. After model calculations are completed, the results are extracted using a MATLAB program. Data on current velocity, direction, tide level, wave height, and wave period are calculated. Data at the grid center are interpolated, and all data are interpolated to the nodes as initial conditions and verification data.

[0044] In this example, the mesoscale FVCOM-SWAVE model internally couples the FVCOM ocean current and SWAVE wave models. The wave-current coupling switch is enabled by compiling the make.inc file, where the initial condition is a cold start at the beginning of the calculation. The initial terrain data is extracted from the chart, and the OpenFOAM model is used to calculate the iterative inversion data in the subsequent calculation process. NAO.99b is used to create the tidal forcing file at the open boundary. The wind field is driven by the gfs reanalysis wind field. The bottom friction coefficient at the initial moment of calculation is taken as the recommended value of 1.6×10 in the East China Sea according to the literature. -3 In the subsequent calculation process, the OpenFOAM model is used to calculate the iterative inversion data and assign values ​​to the sea area partitions.

[0045] Furthermore, an inverse distance weighted interpolation method was used to interpolate the flow velocity, flow direction, tidal level, wave height, and wave period data calculated by the external FVCOM-SWAVE model onto the internal OpenFOAM model boundary. The FVCOM-SWAVE and OpenFOAM models were calculated separately, with data exchanged only at the set time step. This ensured the efficiency of each model while also enabling the dynamic transfer of wave, flow, and bottom friction data.

[0046] Among them, in the calculation sea area, a point is selected every 1000m as an independent bottom friction coefficient, and the arrangement form is plum blossom type. The three-dimensional high-resolution structured or unstructured grid between 0.1m and 10m is set by Hypermesh software. Among them, the grid is calculated in the inner domain of the port pile foundation terminal model, such as Figure 4 As shown in the figure, the sediment scouring and deposition phenomenon at the pile foundation and at each independent bottom friction coefficient calculation point is simulated based on the small-scale OpenFOAM model.

[0047] Specifically, the bottom friction coefficient is determined as follows:

[0048] (1) Taking the area where the port pile foundation terminal is located as the reference point, select one point every 1000m in the calculation sea area as an independent bottom friction coefficient point, and arrange it in a plum blossom shape. The points are covered with FVCOM-SWAVE calculation grids; with these points as the center, set a three-dimensional high-resolution structured grid with a resolution of 0.1m-0m at the location of the points;

[0049] (2) Perform the first calculation of FVCOM-SWAVE; in which the bottom friction coefficient calculation formula built into FVCOM-SWAVE is corrected to the generalized Manning bottom friction coefficient formula related to the water level;

[0050] First, set an overall bottom friction coefficient empirical value based on the sea area experience, such as 0.001 for the Bohai Sea and 0.0016 for the Yellow Sea and East China Sea. Turn on the wave-current coupling switch by compiling the make.inc file, where the initial condition is the cold start at the beginning of the calculation; the initial terrain data is the chart-extracted data; and a tidal forcing file is created at the open boundary.

[0051] The bottom friction coefficient of the initial calculation is calibrated empirically. The judgment method is that the average relative error of the initial calculated significant wave height is less than 30%, the tide level error is less than 15%, the flow direction error is less than 35%, and the flow velocity error is less than 30%. The bottom friction coefficient after calibration becomes the initial value of the bottom friction coefficient.

[0052] Among them, the calculation formula of the built-in bottom friction coefficient of the FVCOM-SWAVE model is:

[0053] ,

[0054] Where k is the Karman constant, is the thickness of the bottom water layer. is the seabed roughness height; since the study area is nearshore, the Manning coefficient used in MIKE 21 is introduced to improve the built-in bottom friction coefficient calculation formula into a generalized Manning bottom friction coefficient;

[0055] Specifically, the generalized Manning-type bottom friction coefficient calculation formula is: ,

[0056] Where n is the Manning roughness coefficient, h is the water depth;

[0057] (3) Dynamic calibration experiment of bottom friction coefficient at each independent bottom friction coefficient point. Substitute the initial value of bottom friction coefficient obtained in (2) into the Openfoam calculation model at each point, and use the FVCOM-SWAVE calculation results in (2), i.e. tide level, flow velocity, flow direction, wave height, and wave period, to perform three-dimensional interpolation to the calculation nodes of Openfoam at each point through the overlapping grid method as initial conditions and verification data;

[0058] The Openfoam three-dimensional hydrodynamic calculation was performed, and the convergence condition of the Openfoam numerical simulation was set to <10 -6 , when the set convergence condition is reached (<10 -6 ), output the current water level and flow rate results, compare them with the measured data, calculate the RMSE root mean square error, and adjust the bottom friction parameter value for the next calibration calculation. Repeat this process until the RMSE no longer changes and is close to 0. It is considered that the bottom friction coefficient is applicable to the range of the point. This is called the dynamic calibration value of the bottom friction coefficient at each point.

[0059] Specifically, the dynamic calibration formula of the bottom friction coefficient is:

[0060] ,

[0061] in, is the bottom friction coefficient at step i; is the bottom friction coefficient at step i-1; is the root mean square error at step i; is the root mean square error at step i-1;

[0062] RMSE root mean square error calculation formula is:

[0063] ,

[0064] in, and are the simulated values ​​and the measured values, respectively, here for tide level and flow velocity; N is the number of sample data. The tide level and flow velocity values ​​generated by the numerical simulation are the simulated values, while the tide level and flow velocity values ​​provided by the buoy and tide station are the measured values;

[0065] (4) The dynamic calibration value of the bottom friction coefficient at each point is used to create the FVCOM-SWAVE bottom friction coefficient block startup file, and the FVCOM-SWAVE calculation is performed. The wave-current coupling switch is turned on by compiling the make.inc file, where the initial condition is the cold start at the beginning of the calculation; the terrain data is the data extracted from the chart; and the tidal forcing file is created at the open boundary.

[0066] (5) Dynamic experiment of sediment bottom friction coefficient at each independent bottom friction coefficient point. The results of the previous FVCOM-SWAVE calculation, namely tide level, flow velocity, flow direction, wave height, and wave period, were interpolated to the calculation nodes of Openfoam at each point through the overlapping grid method in three dimensions as initial conditions and verification data. The Openfoam three-dimensional wave-flow-sediment coupling calculation (including hydrodynamic calculation, sediment calculation, and bed calculation) was performed, and the convergence condition of the Openfoam numerical simulation was set to <10-6. When the set convergence condition (<10 -6 ) and output the current sediment scouring and deposition test results (topographic data after bed scanning). Calculate the bottom friction coefficient at each calculation point based on the current water level and topography, which is the bottom friction coefficient after scouring and deposition.

[0067] (6) Using the bottom friction coefficients after scouring and silting at each point, a block startup file for the FVCOM-SWAVE bottom friction coefficients after scouring and silting was created. The FVCOM-SWAVE calculation was performed. The wave-current coupling switch was enabled by compiling the make.inc file. The initial conditions were the cold start at the beginning of the calculation; the topographic data was extracted from the nautical chart; and a tidal forcing file was created at the open boundary. A large-scale FVCOM-SWAVE wave-current coupling analysis after scouring and silting was performed.

[0068] In this embodiment, the numerical simulation calculation process of the Openfoam model is as follows:

[0069] (1) Hydrodynamic calculation: Specifically, by calculating the RANS equations and turbulent closed equations, the Waves2FOAM tool developed based on the interFoam solver in OpenFOAM is used to generate waves, and the OpenFOAM hydrodynamic model is solved. The VOF method is coupled with the free water surface simulation to capture the propagation deformation of waves around the pile foundation and at each bottom friction parameter point, and the flow velocity, flow direction and free water surface elevation are obtained. The flow velocity and free water surface elevation are compared and verified with the tide level and flow velocity in the results transmitted by FVCOM-SWAVE.

[0070] Specifically, the equation to be solved is:

[0071] ,

[0072] in, p For pressure, is the fluid density, , v is the velocity vector, Reynolds stress vector, g is the gravity acceleration vector, is the Hamilton operator;

[0073] (2) Sediment calculation: Specifically, the OpenFOAM sediment transport model is solved by calculating the bedload and suspended load sediment transport equations. The initial data comes from the OpenFOAM hydrodynamic model calculation results, and the calculation results including sediment transport rate are obtained;

[0074] Specifically, the equation to be solved is:

[0075] ,

[0076] in, To balance the sediment transport rate for bed load, is the velocity of sediment particles, is the probability of sediment movement;

[0077] (3) Calculation of bed deformation: Specifically, the OpenFOAM bed deformation model is solved by solving the sediment continuity equation. The initial data comes from the calculation results of the OpenFOAM sediment transport model to solve the bed deformation around the pile foundation. The convergence condition of the OpenFOAM numerical simulation is set to <10 -6 , and scan the bed surface to obtain the sediment scouring and silting situation around the port pile foundation terminal and at each bottom friction parameter point;

[0078] Specifically, the equation to be solved is:

[0079] ,

[0080] Where, is the bed surface elevation, is the sediment porosity, and represents the exchange of suspended matter near the bed surface, is the bed load transport rate.

[0081] like Figure 5 As shown in the figure, the iterative steps for calculating the bottom friction coefficient / the iterative inversion method for the bottom friction coefficient are as follows: an empirical value of the bottom friction coefficient is assigned in the first calculation, and it is repeatedly calibrated according to verification data such as tide level, wave height, flow velocity, and flow direction until the simulation value no longer changes. This value is taken as the initial value for the calculation, and the FVCOM-SWAVE model is calculated. The obtained flow velocity, flow direction, tide level, wave height, and wave period data are passed to the OpenFOAM model as the initial boundary conditions; a series of tests on pile foundation water blocking and sediment scouring near the pile foundation are carried out based on the OpenFOAM model, and the bottom friction coefficient with the minimum error between the OpenFOAM model and the measured flow velocity is determined by accurately comparing the flow velocity at the measuring point under different working conditions with the flow velocity measured by the buoy.

[0082] Specifically, this embodiment utilizes reanalysis wind data and an open-boundary tidal forcing file, employing the FVCOM-SWAVE model to calculate three-dimensional layered wave-current coupling information, and calculates flow velocity, discharge, tidal level, wave height, and wave period. The calculation results are then transferred to the OpenFOAM grid nodes using a three-dimensional numerical interpolation method as boundary values ​​and verification values. Using the wave-current coupling calculation data arriving at the OpenFOAM model boundary as initial values, the interaction results between waves, currents, sediment, and pile foundations are calculated, and a joint simulation method is established that comprehensively considers mesoscale background flows and small-scale sediment deposition. This method can address the joint simulation of mesoscale wave-current coupling data with the interaction between small-scale port pile foundations, docks, and sediment, thereby capturing multiscale physical phenomena, such as the mutual influence of mesoscale wave-current coupling with dynamic terrain and dynamic bottom friction coefficients, and the sediment scouring and deposition phenomena of small-scale port pile foundations under different wave and current data. Furthermore, the accuracy of the bottom friction coefficient of the mesoscale numerical model is improved. A dynamic sediment scouring and deposition model is calculated using the small-scale numerical model, and the bottom friction parameters are inverted based on the dynamic terrain, water level, and flow velocity calculation data. Therefore, the method of this embodiment can take into account the interaction law between waves, flows, sediments and piles under multi-scale simulation conditions, and improve the accuracy of assigning the bottom friction coefficient in the mesoscale numerical model.

[0083] Example 2: Based on the above, this application also provides a port pile foundation terminal sediment scouring and silting simulation system based on FVCOM-SWAVE and OpenFOAM, which uses the simulation method described above to perform simulation calculation / analysis.

[0084] In summary, this application combines the solution of the mesoscale FVCOM-SWAVE open source model to simulate three-dimensional layered wave-current coupling information and the solution of the full three-dimensional small-scale OpenFOAM open source model to solve the sediment scouring and deposition information, and establishes a multi-scale wave-current sediment pile foundation coupling method; in the outer domain of the joint calculation model, the FVCOM-SWAVE numerical model is used to perform wave-current coupling calculations to obtain wave-current dynamic change data such as flow velocity, flow direction, tide level, wave height, and wave period; in the inner domain of the coupling model, OpenFOAM is used to simulate the sediment scouring and deposition information of the sea area where the small-scale pile foundation is located; compared with the simple OpenFOAM model, the joint simulation calculation method of this application can obtain more accurate wave-current coupling data, thereby reducing the amount of calculation; compared with the simple FVCOM-SWAVE model, it can obtain full three-dimensional small-scale sediment scouring and deposition information in the vicinity of the port pile foundation terminal, thereby improving the accuracy of the bottom friction coefficient assignment and the real-time terrain simulation accuracy.

[0085] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A simulation method for sediment scouring and silting of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM is characterized by: The following steps are involved: S1. Establish an FVCOM-SWAVE model based on the sea area where the port's pile-foundation wharf is located. Based on the measured data on the sediment erosion and deposition patterns of the pile-foundation wharf, multiple OpenFOAM models are established in the FVCOM-SWAVE model calculation area. The FVCOM-SWAVE and OpenFOAM model grids are processed using the overlaid mesh method, with arbitrary overlap between the model grids. S2. Simulate and calculate three-dimensional layered wave-current coupling data based on the FVCOM-SWAVE model. Output parameters include tide level, wave height, wave period, current velocity, and current direction. The initial bottom friction coefficient is the recommended constant for the sea area. The FVCOM-SWAVE model simulation results are repeatedly calibrated until the simulated value no longer changes. S3. Using a three-dimensional numerical interpolation method, the wave-current coupling data calculated by the FVCOM-SWAVE model are interpolated to the grid nodes of the OpenFOAM model; S4. Transfer the wave-current coupling calculation data at the boundary of the FVCOM-SWAVE model to the OpenFOAM model as initial and verification values. Conduct numerical experiments on the water-blocking effect of pile foundations and sediment scouring and deposition based on the OpenFOAM model. Simulation results of the interaction between waves, currents, sediments, and the port pile foundation wharf are obtained through calculations. S5: Analyze the sediment erosion and deposition patterns around the pile calculated by the OpenFOAM model to obtain the current terrain information and bottom friction parameter information around the pile. Import the terrain information into the terrain file of the FVCOM-SWAVE model to update it. Create a bottom friction parameter file suitable for the current sea area as the startup file of the FVCOM-SWAVE model to simulate the dynamic waves and flow conditions around the sediment erosion and deposition pile. S6: Dynamically exchange the boundary conditions calculated by the FVCOM-SWAVE model with the terrain file and bottom friction coefficient file generated by the OpenFOAM model's simulated three-dimensional port pile foundation terminal sediment scouring and deposition information, and compare them with the simulation results at the previous time. The difference in the simulated hydrodynamic environment between the two is used as the basis for judging the impact of changes in the water and sediment environment around the piles.

2. The method for simulating sediment scouring and silting of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM according to claim 1 is characterized in that: The FVCOM-SWAVE model simulates and calculates the mesoscale wave-current coupling in the sea area where the pile foundation is located. The calculated data include tide level, flow velocity, flow direction, wave height, and wave period. The OpenFOAM model simulates and calculates the small-scale sediment scouring and deposition data in the sea area where the pile foundation is located. The calculated data include the terrain parameters and bottom friction coefficient after sediment scouring and deposition.

3. The method for simulating sediment scouring and silting of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM according to claim 2 is characterized in that: The numerical simulation calculation process of the OpenFOAM model includes hydrodynamic calculations; specifically, by calculating the RANS equations and turbulent closed equations, using the Waves2FOAM tool developed based on the interFoam solver in OpenFOAM to generate waves, solve the OpenFOAM hydrodynamic model, and use the VOF method to couple the free water surface simulation to capture the propagation and deformation of waves around the pile foundation and various bottom friction parameter points to obtain the flow velocity, flow direction and free water surface elevation. Among them, the flow velocity and free water surface elevation are compared and verified with the tide level and flow velocity in the results transmitted by FVCOM-SWAVE.

4. The method for simulating sediment scouring and deposition of a pile-foundation port terminal based on FVCOM-SWAVE and OpenFOAM according to claim 3 is characterized in that: The numerical simulation process of the OpenFOAM model also includes sediment calculations. Specifically, the OpenFOAM sediment transport model is solved by calculating the bedload and suspended load sediment transport equations. The initial data comes from the OpenFOAM hydrodynamic model calculation results, and the calculation results, including the sediment transport rate, are obtained.

5. The method for simulating sediment scouring and deposition of a pile-foundation wharf in a port based on FVCOM-SWAVE and OpenFOAM according to claim 4 is characterized in that: The numerical simulation calculation process of the OpenFOAM model also includes the calculation of bed deformation. Specifically, the OpenFOAM bed deformation model is solved by solving the sediment continuity equation. The initial data comes from the calculation results of the OpenFOAM sediment transport model. The deformation of the bed around the pile foundation is solved. The convergence condition of the OpenFOAM numerical simulation is set to <10 -6 , and scan the bed surface to obtain the sediment scouring and siltation situation around the port pile foundation terminal and at each bottom friction parameter point.

6. The method for simulating sediment scouring and deposition of a pile-foundation wharf in a port based on FVCOM-SWAVE and OpenFOAM according to claim 1, characterized in that: The selection points of multiple independent bottom friction coefficients are determined according to the seabed topography. One point is selected every 1000m in the calculation sea area as an independent bottom friction coefficient, and the arrangement form is a plum blossom shape.

7. The method for simulating sediment scouring and deposition of a pile-foundation wharf in a port based on FVCOM-SWAVE and OpenFOAM according to claim 1, characterized in that: The mesh resolution of the FVCOM-SWAVE model in the overlapping area is 1-1.5 times that of the OpenFOAM model in the overlapping area.

8. The method for simulating sediment scouring and deposition of a pile-foundation wharf in a port based on FVCOM-SWAVE and OpenFOAM according to claim 7, characterized in that: The mesh resolution of the OpenFOAM model in the overlapping area ranges from 10m to 50m, and the mesh resolution of the OpenFOAM model in the non-overlapping area ranges from 0.1m to 10m.

9. The method for simulating sediment scouring and deposition of a pile-foundation wharf in a port based on FVCOM-SWAVE and OpenFOAM according to claim 8, characterized in that: The grid resolution of the FVCOM-SWAVE model in the overlapping area ranges from 5m to 75m, and the grid resolution of the FVCOM-SWAVE model in the non-overlapping area ranges from 75m to 300m.

10. The port pile foundation terminal sediment scouring and silting simulation system based on FVCOM-SWAVE and OpenFOAM is characterized by: The simulation method according to any one of claims 1 to 9 is used for simulation calculation / analysis.

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