Research On Automatic Generation Method Of Boundary Layer Mesh For Complex Shape Based On Construction Method

Mesh generation technology is a key part of Computational Fluid Dynamics(CFD),and it is the bottleneck of CFD in practical engineering.With the rapid development of computer technology,CFD plays an increasingly important role in engineering technology fields such as fluid mechanics,aerodynamics,and UAV design.Among them,the generation of the boundary layer mesh is a key step in the mesh generation technology.The good quality of the boundary layer mesh ensures the accuracy of the numerical calculation.When dealing with complex shapes,the current boundary layer mesh generation methods often The algorithm fails.Based on the idea of construction method,this paper proposes a kind of boundary layer mesh generation algorithm that first generates a grid frame,and then generates a grid under the constraints of the grid frame.Compared with the traditional algorithm,the algorithm can effectively avoid the grid intersection phenomenon and has good global consistency.In this paper,we study the mesh generation algorithm of the boundary layer in the complex shape area,and mainly propose the following innovations:(1)Surface mesh segmentation algorithm.Firstly,the characteristic area of the surface mesh is divided by the dihedral angle information of the mesh edge and the mesh point,and then the remaining flat area is divided by the flatness information of the mesh unit.(2)Frame line lifting algorithm.First,the least squares method is used to fit the boundary discrete points,and the error between the fitted point and the discrete point is recorded at the same time,then the fitting point is lifted linearly,and finally the error is restored to complete the construction of the grid frame.(3)The top surface generation algorithm of the boundary layer.Under the condition of frame constraints,the top-level grid points of the boundary layer are generated by the interpolation of the compact radial basis function.(4)Grid intersection processing algorithm.First,the AABB bounding box collision detection algorithm is used to screen out the possible intersecting areas,and then the intersection judgment algorithm between rays and triangular elements is used to detect the real intersecting areas.In order to verify the quality of the mesh generated by the method in this paper,the method in this paper and the commercial mesh generation software Pointwise were used to generate the boundary layer mesh for the complex rocket model.In addition,the surface mesh and the space mesh were generated by the same method.Sets of grids for numerical calculations.Comparing the numerical calculation results of the method in this paper with Pointwise,the comparison of the calculation results shows that the angle of attack-lift curve and lift-drag coefficient curve corresponding to the two sets of grids are basically the same,which shows that the method in this paper is reliable and effective.