等方性乱流中での慣性粒子の衝突現象に対する高効率並列計算法

概要

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This study develops an efficient parallel simulation of colliding particles in stationary isotropic turbulence. Flow is computed with a fourth-order finite-difference method and particles are tracked with the Lagrangian method. Particle collisions are efficiently detected by the cell-index method, which is often used in molecular dynamics simulations. The developed code is written in Fortran 90 in conjunction with MPI library. Auto-parallelization directives are inserted in the code for shared-memory parallelization, making it possible to run the code in the so-called hybrid-parallelization mode. The code is designed to minimize the MPI communication, which results in a high parallel performance. The present simulation has been run on up to 5123 grids with 10 million particles. The largest simulation has successfully obtained the collision frequencies for the Taylor-scale-based Reynolds number, Reλ, of 209, which is much larger than previously attained maximum Reλ of 85 in particle collision simulations. The collision frequencies obtained in this study have shown that a collision frequency model underestimates the frequency in high Reλ flows.