Hybrid Cartesian Grid Method for Moving Boundary Problems  

作　　者：Shen Zhiwei Zhao Ning 

机构地区：[1]College of Aerospace Engineering,Nanjing University of Aeronautics and Astronautics

出　　处：《Transactions of Nanjing University of Aeronautics and Astronautics》2016年第1期37-44,共8页南京航空航天大学学报（英文版）

基　　金：supported partly by the National Basic Research Program of China(″973″Program)(No.2014CB046200)

摘　　要：A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems. The near body region is discretized by using the body-fitted structured grids, while the remaining computational domain is tessellated with the generated Cartesian grids. As the body moves, the structured grids move with the body and the outer boundaries of inside grids are used to generate new holes in the outside adaptive Cartesian grid to facilitate data communication. By using the alternating digital tree （ADT） algorithm, the computational time of hole-cutting and identification of donor cells can be reduced significantly. A compressible solver for unsteady flow problems is developed. A cell-centered, second-order accurate finite volume method is employed in spatial discreti- zation and an implicit dual-time stepping low-upper symmetric Gauss-Seidei （LU-SGS） approach is employed in temporal discretization. Geometry-based adaptation is used during unsteady simulation time steps when boundary moves and the flow solution is interpolated from the old Cartesian grids to the new one with inverse distance weigh- ting interpolation formula. Both laminar and turbulent unsteady cases are tested to demonstrate the accuracy and efficiency of the proposed method. Then, a 2-D store separation problem is simulated. The result shows that the hybrid Cartesian grid method can handle the unsteady flow problems involving large-scale moving boundaries.A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems.The near body region is discretized by using the body-fitted structured grids,while the remaining computational domain is tessellated with the generated Cartesian grids.As the body moves,the structured grids move with the body and the outer boundaries of inside grids are used to generate new holes in the outside adaptive Cartesian grid to facilitate data communication.By using the alternating digital tree(ADT)algorithm,the computational time of hole-cutting and identification of donor cells can be reduced significantly.A compressible solver for unsteady flow problems is developed.A cell-centered,second-order accurate finite volume method is employed in spatial discretization and an implicit dual-time stepping low-upper symmetric Gauss-Seidel(LU-SGS)approach is employed in temporal discretization.Geometrybased adaptation is used during unsteady simulation time steps when boundary moves and the flow solution is interpolated from the old Cartesian grids to the new one with inverse distance weighting interpolation formula.Both laminar and turbulent unsteady cases are tested to demonstrate the accuracy and efficiency of the proposed method.Then,a 2-D store separation problem is simulated.The result shows that the hybrid Cartesian grid method can handle the unsteady flow problems involving large-scale moving boundaries.

关 键 词：hybrid Cartesian grid l moving boundary alternating digital tree （ADT） algorithm unsteady flow 

分 类 号：V211.3[航空宇航科学与技术—航空宇航推进理论与工程]