Port pile foundation wharf sediment erosion and deposition simulation method and system based on FVCOM-SWAVE and OpenFOAM

Abstract

The invention discloses a port pile foundation wharf sediment erosion and deposition simulation method and system based on FVCOM-SWAVE and OpenFOAM, and the method comprises the steps: building an FVCOM-SWAVE model according to a sea area where a port pile foundation wharf is located, and building a plurality of OpenFOAM models according to the actual measurement data of the sediment erosion and deposition form of the pile foundation wharf in combination with the calculation area of the FVCOM-SWAVE model; wave flow coupling calculation data, transmitted to the boundary of the OpenFOAM model, of the FVCOM-SWAVE model serves as an initial value and a verification value, a pile foundation water blocking effect and sediment erosion and deposition numerical test based on the OpenFOAM model is carried out, and a simulation result of interaction of waves, flow, sediment and a port pile foundation wharf is obtained through calculation; and dynamically exchanging boundary conditions calculated by the FVCOM-SWAVE model and a topographic file and a bottom friction coefficient file which are made by three-dimensional port pile foundation wharf sediment erosion and deposition information simulated by the OpenFOAM model, comparing the topographic file and the bottom friction coefficient file with simulation results at previous moments, and taking hydrodynamic environment difference simulated by the topographic file and the bottom friction coefficient file as a judgment basis for influence of pile surrounding water and sediment environment change.

Description

Technical Field

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

[0002] The port pile foundation wharf is a common port wharf form. Due to the uniqueness of the site selection, it is directly affected by waves, currents, and sediments. The marine environment is often complex and changeable. The pile group will also affect the dynamic conditions of nearshore waves, currents, and sediments. In addition, there is often serious sedimentation near the pile foundation. Therefore, the influence of wave and current forces in the sea area around the port pile foundation wharf, as well as the movement of sediments around the pile foundations and the changes in sediment scouring and silting should be considered.

[0003] The numerical simulation technology currently used is often of a single scale, or a single description of the mesoscale ocean dynamics in the sea area where the port pile foundation terminal is located, or a single description of the small-scale sediment accumulation in the sea area where the port pile foundation terminal is located. For example, the single use of the FVCOM-SWAVE mode for numerical simulation can calculate the mesoscale background flow, and the effect is good, but it cannot accurately simulate the subtle water flow conditions when the tide and waves act on the pile foundation, and cannot describe the sediment accumulation of the pile foundation in detail; the single use of the OpenFOAM model for numerical simulation can accurately simulate the subtle water flow conditions when the tide and waves act on the pile foundation and describe the sediment accumulation of the pile foundation in detail, with high calculation accuracy, but it cannot quickly simulate the effect of the mesoscale background flow on sediment and pile foundation.

[0004] Therefore, a method and system for silt scouring and siltation simulation of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM is provided, which can accurately and quickly perform comprehensive simulation calculations on silt 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 scouring and silting of port pile foundation wharf based on FVCOM-SWAVE and OpenFOAM, which accurately evaluates and predicts the scouring and silting process of port pile foundation wharf through the calculation method of spatiotemporal variation bottom friction coefficient through small-scale digital model inversion.

[0006] The invention discloses a method for simulating silt scouring and silting of a port pile foundation wharf based on FVCOM-SWAVE and OpenFOAM, comprising the following steps: S1. According to the sea area where the port pile foundation wharf is located, the FVCOM-SWAVE model is established, and according to the measured data of the sediment scouring and silting morphology of the pile foundation wharf, multiple OpenFOAM models are established in combination with the calculation area of ​​the FVCOM-SWAVE model; among them, the overlapping grid method is used to process the FVCOM-SWAVE and OpenFOAM model grids, and the model grids are arbitrarily overlapped; S2. Based on the FVCOM-SWAVE model, the three-dimensional layered wave-current coupling data are simulated and calculated, and the output parameters include tide level, wave height, wave period, flow velocity and flow direction; among them, the initial bottom friction coefficient takes the recommended constant of the sea area, and the simulation calculation results of the FVCOM-SWAVE model are repeatedly calibrated until the simulation value no longer changes; S3. Using the 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. The wave-current coupling calculation data (i.e., the interpolation data in S3) at the boundary of the FVCOM-SWAVE model is transferred to the OpenFOAM model as the initial value and verification value, and numerical tests on the water blocking effect of pile foundation and sediment scouring and deposition based on the OpenFOAM model are carried out. The simulation results of the interaction between waves, currents, sediments and the pile foundation of the port are obtained by calculation; S5: Analyze the sediment scouring and silting morphology around the pile calculated by the OpenFOAM model to obtain the terrain information and bottom friction parameter information around the pile at the current moment, import the terrain information into the terrain file of the FVCOM-SWAVE model for updating, and make a bottom friction parameter file suitable for the sea area at the current moment as the startup file of the FVCOM-SWAVE model to simulate the dynamic waves and flow conditions around the sediment scouring and silting pile; S6: Dynamically exchange the boundary conditions calculated by the FVCOM-SWAVE model and the terrain file and bottom friction coefficient file produced by the OpenFOAM model to simulate the 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 hydrodynamic environment simulated by the two is used as the basis for judging the impact of changes in the water and sediment environment around the piles.

[0007] 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.

[0008] The numerical simulation calculation process of the Openfoam model includes hydrodynamic calculations; 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, the OpenFOAM hydrodynamic model is solved, and the VOF method is used to couple the free water surface simulation to capture the propagation 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.

[0009] The numerical simulation calculation process of the OpenFOAM model also includes sediment calculation; specifically: by calculating the bedload and suspended load sediment transport equations, the OpenFOAM sediment transport model is solved, where the initial data comes from the calculation results of the OpenFOAM hydrodynamic model, and the calculation results including the sediment transport rate are obtained.

[0010] 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 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 silt scouring and silting conditions around the port pile foundation terminal and at each bottom friction parameter point.

[0011] 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.

[0012] 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.

[0013] The grid resolution of the OpenFOAM model in the overlapping area ranges from 10m to 50m, and the grid resolution of the OpenFOAM model in the non-overlapping area ranges from 0.1m to 10m.

[0014] 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.

[0015] Furthermore, the present invention also provides a port pile foundation terminal silt scouring and silting simulation system based on FVCOM-SWAVE and OpenFOAM, which uses the simulation method as described above to perform simulation calculation / analysis.

[0016] The technical solution of the present invention has the following advantages: In the present invention, a joint simulation method that comprehensively considers mesoscale background flow and small-scale silt deposition is established, and the joint simulation problem of the interaction between mesoscale wave-current coupling data and small-scale port pile foundation wharf and sediment is solved, so as to obtain multi-scale physical phenomena, such as the mutual influence of mesoscale wave-current coupling and dynamic terrain and dynamic bottom friction coefficient, and the silt scouring and siltation phenomenon of small-scale port pile foundation wharf under different wave-current data; and the bottom friction coefficient accuracy of the mesoscale numerical model is improved, and the dynamic silt scouring and siltation model is obtained by calculating the small-scale numerical model, and the bottom friction parameters are inverted according to the dynamic terrain, water level and flow velocity calculation data, so as to accurately and quickly evaluate and predict the silt scouring and siltation process of the port pile foundation wharf. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the method for simulating silt scouring and silting of a port pile foundation wharf according to the present invention; Figure 2 A schematic diagram of overlapping grids for calculating inner and outer domains according to the present invention; Figure 3 A schematic diagram of a mesoscale grid in the FVCOM-SWAVE model of the present invention; Figure 4 A schematic diagram of a small-scale grid of the OpenFOAM model of the present invention; Figure 5 This is a flow chart of assigning independent bottom friction coefficient according to the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Example 1: Figure 1As shown, this embodiment provides a method for simulating sediment scouring and silting of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM, comprising the following steps: S1. According to the sea area where the port pile foundation wharf is located, the FVCOM-SWAVE model is established, and according to the measured data of the sediment scouring and silting morphology of the pile foundation wharf, multiple OpenFOAM models are established in combination with the calculation area of ​​the FVCOM-SWAVE model; among them, the overlapping grid method is used to process the FVCOM-SWAVE and OpenFOAM model grids, and the model grids are arbitrarily overlapped; S2. Based on the FVCOM-SWAVE model, the three-dimensional layered wave-current coupling data are simulated and calculated, and the output parameters include tide level, wave height, wave period, flow velocity and flow direction; among them, the initial bottom friction coefficient takes the recommended constant of the sea area, and the simulation calculation results of the FVCOM-SWAVE model are repeatedly calibrated until the simulation value no longer changes; S3. Using the 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. The wave-current coupling calculation data (i.e., the interpolation data in S3) at the boundary of the FVCOM-SWAVE model is transferred to the OpenFOAM model as the initial value and verification value, and numerical tests on the water blocking effect of pile foundation and sediment scouring and deposition based on the OpenFOAM model are carried out. The simulation results of the interaction between waves, currents, sediments and the pile foundation of the port are obtained by calculation; S5: Analyze the sediment scouring and silting morphology around the pile calculated by the OpenFOAM model to obtain the terrain information and bottom friction parameter information around the pile at the current moment, import the terrain information into the terrain file of the FVCOM-SWAVE model for updating, and make a bottom friction parameter file suitable for the sea area at the current moment as the startup file of the FVCOM-SWAVE model to simulate the dynamic waves and flow conditions around the sediment scouring and silting pile; S6: Dynamically exchange the boundary conditions calculated by the FVCOM-SWAVE model and the terrain file and bottom friction coefficient file produced by the OpenFOAM model to simulate the 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 hydrodynamic environment simulated by the two is used as the basis for judging the impact of changes in the water and sediment environment around the piles.

[0022] 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.

[0023] Among them, multiple independent bottom friction coefficient selection points are determined according to the seabed topography, and one point is selected every 1000m in the calculation sea area as the independent bottom friction coefficient, and the arrangement form is a plum blossom shape; in this embodiment, the first point is the location of the pile foundation wharf, and then the pile foundation wharf is expanded outward in a plum blossom shape. In places where the terrain changes greatly, such as where the adjacent height difference is greater than 600m, additional points are added.

[0024] 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.

[0025] 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 the OpenFOAM model are generated on the multiple sets of sub-areas. The schematic diagram of the overlapping grid of the pile foundation calculation area is shown in the figure. 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. In the coupled calculation process of waves, flows, 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 sub-areas is transmitted through the interpolation of grid nodes in the overlapping area.

[0026] 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 3 As shown in the figure, the mesoscale FVCOM model is used to simulate the three-dimensional stratified tidal current and wave motion in a large area of ​​the sea area. The original equation of the FVCOM model is a Reynolds-averaged three-dimensional ocean control equation group, which includes the water body continuity equation and momentum equation, temperature, salinity equation and turbulence equation, etc.; the FVCOM original equation group can be solved by semi-implicit method or mode splitting; FVCOM uses unstructured triangular grids in the horizontal direction, and σ coordinates, s coordinates and mixed coordinate systems in the vertical direction. After the model calculation is completed, the calculation results are extracted based on the matlab program, and the flow velocity, flow direction, tide level, wave height and wave period data are statistically analyzed. The data at the center of the grid are interpolated, and all data are interpolated to the nodes as initial conditions and verification data.

[0027] In this embodiment, the mesoscale FVCOM-SWAVE model internally couples the FVCOM ocean current and SWAVE ocean wave models. 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 initial terrain data is the chart extraction data, and the OpenFOAM model is used to calculate the iterative inversion data in the subsequent calculation process; NAO.99b is used to make 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 is calculated according to the literature and the recommended value of 1.6×10 in the East China Sea. -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.

[0028] Furthermore, the inverse distance weighted interpolation method is used to interpolate the velocity, flow direction, tide level, wave height, and wave period data calculated by the external domain FVCOM-SWAVE model to the boundary of the internal domain OpenFOAM model. The FVCOM-SWAVE model and the OpenFOAM model are calculated separately, and data is exchanged only when the set time step is reached, which ensures the efficiency of each calculation while realizing the dynamic transmission of wave, flow, bottom friction and other data.

[0029] Among them, a point is selected every 1000m in the calculation sea area 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 silting phenomenon at the pile foundation and each independent bottom friction coefficient calculation point is simulated based on the small-scale OpenFOAM model.

[0030] Specifically, the bottom friction coefficient is determined as follows: (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 between 0.1m and 0m at the point location; (2) Perform the first calculation of FVCOM-SWAVE; 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; First, an overall bottom friction coefficient empirical value is set according to the sea area empirical value, such as 0.001 in the Bohai Sea, and 0.0016 in the Yellow Sea and the East China Sea; 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 initial terrain data is the data extracted from the chart; and the tidal level forcing file is made at the open boundary; The empirical value of the bottom friction coefficient calculated initially is calibrated, where the judgment method is that the average relative error of the effective wave height calculated initially 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; Among them, the calculation formula of the built-in bottom friction coefficient of the FVCOM-SWAVE model is: , Where k is the Karman constant, is the thickness of the bottom water layer. is the seabed roughness height; considering that the study area is a nearshore sea area, 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; Specifically, the generalized Manning-type bottom friction coefficient calculation formula is: , Where n is the Manning roughness coefficient, h is the water depth; (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; 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 (<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, and 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, which is called the dynamic calibration value of the bottom friction coefficient at each point. Specifically, the dynamic determination formula of the bottom friction coefficient is: , 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 the i-th step; is the root mean square error at the i-1th step; RMSE root mean square error calculation formula is: , in, and are the simulated value and the measured value, respectively, here they are the tide level and flow velocity values; 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; (4) The dynamic rate 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 nautical chart; and the tidal forcing file is created at the open boundary.

[0031] (5) Dynamic experiment of bottom friction coefficient of sediment erosion and siltation at each independent bottom friction coefficient point. The calculation results of FVCOM-SWAVE in the previous step, namely tide level, flow velocity, flow direction, wave height, and wave period, are interpolated to the calculation nodes of Openfoam at each point through the overlapping grid method in three dimensions as initial conditions and verification data. Openfoam three-dimensional wave-flow-sediment coupling calculation (including hydrodynamic calculation, sediment calculation, and bed calculation) is performed, and the convergence condition of Openfoam numerical simulation is set to <10-6. When the set convergence condition (<10 -6 ) and output the current sediment scouring and silting test results (topographic data after bed scanning). The bottom friction coefficient of each calculation point at this time is calculated based on the water level and topography at this time, which is the bottom friction coefficient after scouring and silting.

[0032] (6) Use the bottom friction coefficient after scouring and silting at each point to create the FVCOM-SWAVE bottom friction coefficient after scouring and silting block startup file, perform FVCOM-SWAVE calculations, and 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 terrain data is the data extracted from the nautical chart; and the tidal level forcing file is created at the open boundary. Calculate the large-scale FVCOM-SWAVE wave-current coupling analysis after scouring and silting.

[0033] In this embodiment, the numerical simulation calculation process of the Openfoam model is as follows: (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, solve the OpenFOAM hydrodynamic model, and use the VOF method to couple the free water surface simulation to capture the propagation deformation of waves around the pile foundation and at each bottom friction parameter point, and obtain the flow velocity, flow direction and free water surface elevation. 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; Specifically, the equation to be solved is: , 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; (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 calculation results of the OpenFOAM hydrodynamic model, and the calculation results including the sediment transport rate are obtained. Specifically, the equation to be solved is: , in, To balance the sediment transport rate for bed load, is the velocity of sediment particles, is the probability of sediment movement; (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 wharf and at each bottom friction parameter point; Specifically, the equation to be solved is: , In the formula, 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.

[0034] like Figure 5As 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: the empirical value of the bottom friction coefficient is assigned in the first calculation, and it is repeatedly calibrated according to the verification data such as tide level, wave height, flow velocity, flow direction, etc. until the simulation value no longer changes, and this value is taken as the initial value for calculation, and the FVCOM-SWAVE model is calculated, and 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 measured flow velocity of the buoy.

[0035] That is, this embodiment uses the reanalysis wind field data and the open boundary tide level forcing file, adopts the FVCOM-SWAVE model to calculate and obtain the three-dimensional layered wave-current coupling information, calculates the flow velocity, flow, tide level, wave height, and wave period, and uses the three-dimensional numerical interpolation method to transfer the calculation results to the OpenFOAM grid node as the boundary value and verification value; the wave-current coupling calculation data reaching the boundary of the OpenFOAM model is used as the initial value, and the results of the interaction between waves, currents, sediments, and pile foundations are obtained by calculation, and a set of joint simulation methods that comprehensively consider the mesoscale background flow and small-scale sediment deposition are established, which can solve the joint simulation problem of the interaction between the mesoscale wave-current coupling data and the small-scale port pile foundation wharf and sediment, thereby obtaining multi-scale physical phenomena, such as the mutual influence of the mesoscale wave-current coupling and the dynamic terrain and the dynamic bottom friction coefficient, and the sediment scouring and silting phenomenon of the small-scale port pile foundation wharf under different wave and current data; and improves the bottom friction coefficient accuracy of the mesoscale numerical model, and obtains the dynamic sediment scouring and silting model through the small-scale numerical model calculation, and inverts the bottom friction parameters according to the dynamic terrain and water level and velocity calculation data. Therefore, the method of this embodiment can take into account the interaction law between waves, currents, sediments and piles under multi-scale simulation conditions, and improve the accuracy of assigning the bottom friction coefficient in the mesoscale numerical model.

[0036] Example 2: Based on the above, the present application also provides a port pile foundation terminal silt scouring and silting simulation system based on FVCOM-SWAVE and OpenFOAM, which uses the simulation method described above for simulation calculation / analysis.

[0037] In summary, this application combines the solution of the mesoscale FVCOM-SWAVE open source model to simulate the 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 silting 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 silting information in 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, the full three-dimensional small-scale sediment scouring and silting information in the vicinity of the port pile foundation terminal can be obtained, thereby improving the accuracy of the bottom friction coefficient assignment and the real-time terrain simulation accuracy.

[0038] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A simulation method for sediment scouring and silting of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM, characterized in that: The following steps are involved: S1. According to the sea area where the port pile foundation wharf is located, the FVCOM-SWAVE model is established, and according to the measured data of the sediment scouring and silting morphology of the pile foundation wharf, multiple OpenFOAM models are established in combination with the calculation area of ​​the FVCOM-SWAVE model; among them, the overlapping grid method is used to process the FVCOM-SWAVE and OpenFOAM model grids, and the model grids are arbitrarily overlapped; S2. Based on the FVCOM-SWAVE model, the three-dimensional layered wave-current coupling data are simulated and calculated, and the output parameters include tide level, wave height, wave period, flow velocity and flow direction; among them, the initial bottom friction coefficient takes the recommended constant of the sea area, and the simulation calculation results of the FVCOM-SWAVE model are repeatedly calibrated until the simulation value no longer changes; S3. Using the 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. The wave-current coupling calculation data at the boundary of the FVCOM-SWAVE model was transferred to the OpenFOAM model as the initial value and verification value, and numerical tests on the water blocking effect of pile foundation and sediment scouring and silting based on the OpenFOAM model were carried out. The simulation results of the interaction between waves, currents, sediments and the pile foundation of the port were obtained by calculation; S5: Analyze the sediment scouring and silting morphology around the pile calculated by the OpenFOAM model to obtain the terrain information and bottom friction parameter information around the pile at the current moment, import the terrain information into the terrain file of the FVCOM-SWAVE model for updating, and make a bottom friction parameter file suitable for the sea area at the current moment as the startup file of the FVCOM-SWAVE model to simulate the dynamic waves and flow conditions around the sediment scouring and silting pile; S6: Dynamically exchange the boundary conditions calculated by the FVCOM-SWAVE model and the terrain file and bottom friction coefficient file produced by the OpenFOAM model to simulate the 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 hydrodynamic environment simulated by 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, 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.

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, the Waves2FOAM tool developed based on the interFoam solver in OpenFOAM is used to generate waves, the OpenFOAM hydrodynamic model is solved, and the VOF method is used to couple the free water surface simulation to capture the propagation 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 silting of a port pile foundation terminal based on FVCOM-SWAVE and OpenFOAM according to claim 3 is characterized in that: The numerical simulation calculation process of the OpenFOAM model also includes sediment calculation; specifically: by calculating the bedload and suspended load sediment transport equations, the OpenFOAM sediment transport model is solved, where the initial data comes from the calculation results of the OpenFOAM hydrodynamic model, and the calculation results including the sediment transport rate are obtained.

5. The method for simulating sediment scouring and silting of a pile foundation wharf of a port based on FVCOM-SWAVE and OpenFOAM according to claim 4, 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 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 silt scouring and silting conditions around the port pile foundation terminal and at each bottom friction parameter point.

6. The method for simulating sediment scouring and silting of a pile foundation wharf of 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 plum blossom type.

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

9. The method for simulating sediment scouring and silting of a pile foundation wharf of 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 simulation system based on FVCOM-SWAVE and OpenFOAM is characterized by: It adopts the simulation method as described in any one of claims 1 to 9 to perform simulation calculation / analysis.

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