An efficient parallel simulation of interacting inertial particles in homogeneous isotropic turbulence
An efficient parallel simulation of interacting inertial particles in homogeneous isotropic turbulence
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DOI：
10.1016/j.jcp.2013.02.027
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发表时间：
2013-06
期刊：
影响因子：
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通讯作者：
R. Onishi;Keiko Takahashi;J. C. Vassilicos
中科院分区：
文献类型：
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作者：
R. Onishi;Keiko Takahashi;J. C. Vassilicos
本研究利用一种新开发的高效并行模拟程序对各向同性湍流中相互作用的惯性粒子进行了并行模拟。流量计算与四阶有限差分法和粒子跟踪与拉格朗日方法。为了研究多个颗粒间的流体动力学相互作用，开发并实现了一种基于二进制的叠加方法。代码采用MPI库进行分布式内存并行化，并设计成最小化MPI通信，从而导致高并行性能。该代码已经运行，以获得碰撞统计的单分散系统与St=0.4的颗粒，其中St是斯托克斯数表示的粒子弛豫时间相对于柯尔莫哥洛夫时间。得到的泰勒微尺度雷诺数Rλ范围为54.9 ~ 527。最大的模拟计算了20003个网格和10003（十亿）个粒子的流动。数值结果表明，当Rλ<100时，碰撞核增大，当Rλ增大时，碰撞核减小.这种雷诺依赖性归因于接触处的径向分布函数，其测量颗粒聚集对碰撞核的贡献。结果还表明，流体动力学相互作用的St=0.4的颗粒减少的径向相对速度和径向分布函数在接触，导致碰撞效率小于1。当Rλ<200时，碰撞效率随R λ的增加从0.65增加到0.75，然后达到饱和。
This study has conducted parallel simulations of interacting inertial particles in statistically-steady isotropic turbulence using a newly-developed efficient parallel simulation code. Flow is computed with a fourth-order finite-difference method and particles are tracked with the Lagrangian method. A binary-based superposition method has been developed and implemented in the code in order to investigate the hydrodynamic interaction among many particles. The code adopts an MPI library for a distributed-memory parallelization and is designed to minimize the MPI communication, which leads to a high parallel performance. The code has been run to obtain collision statistics of a monodisperse system with St=0.4 particles, where St is the Stokes number representing the particle relaxation time relative to the Kolmogorov time. The attained Taylor-microscale based Reynolds number Rλranges from 54.9 to 527. The largest simulation computed the flow on 20003grids and 10003(one billion) particles. Numerical results have shown that the collision kernel increases for Rλ<100 then decreases as Rλincreases. This Reynolds dependency is attributed to that of the radial distribution function at contact, which measures the contribution of particle clustering to the collision kernel. The results have also shown that the hydrodynamic interaction for St=0.4 particles decreases both the radial relative velocity and radial distribution function at contact, leading the collision efficiency less than unity. The collision efficiency increases from 0.65 to 0.75 as Rλincreases for Rλ<200 and then saturates.