基于“神威·太湖之光”的三维有限长方柱绕流直接数值模拟

Direct numerical simulation of flow around a 3D finite square cylinder using the Sunway Taihu Light

[目的]旨在探索基于国产处理器的异构超算平台在船舶水动力学领域的应用效果。[方法]基于“神威·太湖之光”超级计算机,采用MPI+Athread的编程方法,对雷诺数Re=250的三维有限长方柱绕流进行直接数值模拟,并对模拟结果进行验证与分析。模拟使用的网格规模最大达到245.76百万(t=600 s,dt=0.001),并行规模最高达到133 120核。[结果]经统计,在133 120核并行规模下245.76百万网格规模计算能够在数天之内完成。模拟结果显示,在三维有限长方柱绕流流动中,方柱各横截面具有同步涡脱的特征;对比不同长径比方柱绕流尾流场,发现长径比为2时的尾流涡系结构呈现出长直状的流向涡二次结构,而大于2时则为反对称卡门涡。[结论]模拟表明,基于“神威·太湖之光”超级计算机的多级并行计算可有效减少小尺度网格下因规模提升所导致的时间成本,在船舶水动力学领域有较好的应用潜力。

[Objective]This paper aims to study the application effects of heterogeneous supercomputing platforms based on domestic processors in the field of ship hydrodynamics.[Methods]The direct numerical simulation of the flow around a 3D finite square cylinder with Re = 250 using the Sunway Taihu Light supercomputer is implemented, in which the maximum number of grids is 245.76 million( t = 600 s, dt = 0.001),and the simulation results are analyzed and verified. The parallel programming method of MPI+Threads is used with a maximum parallel size of 133 120 cores.[Results]According to the statistics, the calculation can be completed in a few days under the current parallel scale using 245.76 million grids. In addition, the simulation results show that the vortex shedding is synchronous in different cross-sections of a 3D finite square cylinder. When the characteristics of flow around the finite square cylinder with slenderness ratios of 2, 3 and4 are compared, it is found that when the slenderness ratio is 2, the wake vortex structure of the wake is a long straight streamwise vortex secondary structure, or else it is an antisymmetric Karman vortex.[Conclusion]These results indicate that multilevel parallel computing using the Sunway Taihu Light supercomputer can effectively reduce the time-consumption caused by grid scale increase in small-scale grids, which has broad application prospects in the field of ship hydrodynamics.