Standardized Method And Experimental Verification Of CFD Simulation Of Wind Field In Complex Mountainous Area

For the design of wind turbines,transmission lines,long-span bridges and other infrastructure in complex mountainous areas,it is an important task to simulate the wind field.In this paper,a standardized method for CFD(Computational Fluid Dynamics)simulation of complex mountain wind field is established and verified by experiments.The purpose of this paper is to provide a relatively unified and effective method for numerical simulation and parameter setting of wind field in complex mountainous areas.On the one hand,the vegetation of mountainous terrain will affect the flow field.To solve this problem,the influence of rough wall on flow field is simulated based on genetic optimization algorithm.On the other hand,large-scale regional computing in complex mountainous areas requires a lot of grid,computing resources and computing time,and the process of processing input data is very complicated and requires a variety of different software at the same time.To solve this problem,based on the MATLAB GUI wind speed ratio integrated calculation platform,the large-scale modular numerical simulation of complex mountainous area is realized.The calculation parameters of different complexity modular mountainous terrain are compared and analyzed,and the recommended values are given.Taking the real complex mountain terrain of Da Jin Dao,Taishan City,Guangdong Province as the research object,the LES(large eddy simulation)turbulence model is used to conduct CFD numerical simulation research,and the numerical simulation results are compared with the PIV wind tunnel test results to determine the calculation parameters.The mesh is studied in detail,and the dimension of the feature grid is determined for the complex mountainous terrain.And the influence of scale effect on wind field flow is also studied.The results show that the influence of the mesh size and Reynolds number on the results is not obvious.The results will be more accurate when the fine grid is used at the corner of the mountain with a large degree of surface fluctuation and fold.The results show that the results of CFD numerical simulation and wind tunnel test are consistent.There are differences between the two sides,the maximum relative error is 12.84%,the minimum relative error is 4.66%,and the average relative error is 8.81%.In the numerical wind tunnel,the generalized canopy resistance model based on genetic optimization algorithm takes the average relative error of the vertical mean wind profile measured by the offspring and the test as the objective function of the problem to be optimized,and searches the optimal comprehensive resistance coefficient near the wall.Based on MATLAB platform,the control equation of large eddy simulation is given by self programming method,The rough underlying surface of atmospheric boundary layer is used to simulate wind tunnel test.Based on the generalized canopy resistance model,the average relative error between the wind speed at the monitoring location and the wind tunnel test data is reduced from 8.01%to 4.99%,which reduces the error by 37.7%.Based on the existing software environment(GAMBIT,FLUENT,MATLAB,STAR CCM+)and SRTM1 V3.0 global digital elevation database,an integrated platform of wind speed ratio based on MATLAB GUI is established.DEM elevation data within the specified range is intercepted for terrain modeling,boundary transition zone smoothing,grid generation,boundary condition definition,and so on Solving parameter setting,fluent calculation of specified wind direction and post-processing of wind speed ratio results.The computational parameters of grid size,blocking rate,boundary conditions and transition zone length of mountainous terrain with different complexity are compared and analyzed by CFD method.The recommended values of the parameters are as follows:the basic size is 300 m,the first layer grid size is 1/16of the basic size,which is less than the original resolution of terrain(30 m),and the growth rate of prism layer is 1.15,The number of prism layers is 10;For flat terrain,medium complex terrain and complex terrain,the height of 8%,6%and 3%blocking rate is taken as the calculation domain height of each terrain.Compared with the wind tunnel test results,the average relative error is 5.5%.The length of transition region for flat terrain,medium complex terrain and complex terrain is x_L=25h,x_L=15h and x_L=9h.In summary,the standardized method of CFD simulation for complex mountain wind field established in this paper omits the tedious steps from terrain modeling to calculation parameter setting and post-processing,provides a low threshold analysis method for complex mountain wind field,greatly improves the calculation efficiency,and endows the general software with wind engineering characteristics,It breaks through the bottleneck of high number of grids,poor convergence,long calculation time and low calculation efficiency in large-scale wind field simulation of complex mountainous area.