Numerical Simulation of ATPS Parachute Transient Dynamics Using Fluid-Structure Interaction Method

In order to simulate and analyze the dynamic characteristics of the parachute from advanced tactical parachute system(ATPS),a nonlinear finite element algorithm and a preconditioning finite volume method are employed and developed to construct three dimensional parachute fluid-structure interaction(FSI)model.Parachute fabric material is represented by membrane-cable elements,and geometrical nonlinear algorithm is employed with wrinkling technique embedded to simulate the large deformations of parachute structure by applying the NewtonRaphson iteration method.On the other hand,the time-dependent flow surrounding parachute canopy is simulated using preconditioned lower-upper symmetric Gauss-Seidel(LU-SGS)method.The pseudo solid dynamic mesh algorithm is employed to update the flow-field mesh based on the complex and arbitrary motion of parachute canopy.Due to the large amount of computation during the FSI simulation,massage passing interface(MPI)parallel computation technique is used for all those three modules to improve the performance of the FSI code.The FSI method is tested to simulate one kind of ATPS parachutes to predict the parachute configuration and anticipate the parachute descent speeds.The comparison of results between the proposed method and those in literatures demonstrates the method to be a useful tool for parachute designers.

Parallel Region Reconstruction Technique for Sunway High-Performance Multi-core Processors

The leading way to achieve thread-level parallelism on the Sunwayhigh-performance multicore processors is to use OpenMP programming techniques.In order to address the problem of low parallel efficiency caused by highthread group control overhead in the compilation of Sunway OpenMP programs,this paper proposes the parallel region reconstruction technique. The parallelregion reconstruction technique expands the parallel scope of parallel regionsin OpenMP programs by parallel region merging and parallel region extending.Moreover, it reduces the number of parallel regions in OpenMP programs,decreases the overhead of frequent creation and convergence of thread groups,and converts standard fork-join model OpenMP programs to higher performanceSPMD modelOpenMP programs. On the Sunway 1621 server computer, NPB3.3-OMP and SPEC OMP2012 achieved 8.9% and 7.9% running efficiency improvementrespectively through parallel region reconstruction technique. As a result,the parallel region reconstruction technique is feasible and effective. It providestechnical support to fully exploit the multi-core parallelism advantage of Sunway’shigh-performance processors.