圆柱绕流运动的GHM模拟

Numerical Simulation of Flow Motion Around a Circular Cylinder Using Granule Hydrodynamics Method

基于颗粒流体动力学方法（GHM）对不同雷诺数（Re为80～1646）状态下的圆柱绕流问题进行模拟。结果显示。当月仁80时。在圆柱下游有一对较为对称的附着涡；随着雷诺数的增大，流动变得不稳定，圆柱后方的一对附着涡逐渐脱落消失。尾流逐渐变窄。通过圆柱绕流现象的算例研究，讨论了GHM的特点和需要进一步研究的问题。颗粒流体力学方法将流体视为一个离散的系统．将流场离散为弹性流体颗粒，采用赫兹碰撞理论研究颗粒之间的本构关系，处理颗粒所受到的碰撞力：采用帕斯卡原理和声速导数状态方程研究流场的密度差引起的压强差变化，处理颗粒受到的压差力。颗粒流体动力学方法不同于基于流体为连续体假设所建立的N—S方程，具有一定的原始创新意义。

Flow around a cireular cylinder with different Reynolds numbers （Re is 80-1646） is numerically studied by using Granule Hydrodynamics Method （GHM）, and the significant flow characteristics are gained. On the basis of actual simulation, the characters of GHM and the problems for further research are discussed. The GHM thinks the fluid as a discrete system, the fluid field in the system is made up by fluid granules, and the reasons for the fluid motion are fluid granule elastic collision and density difference （pressure difference）. GHM has got the law of fluid motion based on the constitutive relation built by the equation of state, Pascal principle, and the speed equation of sound in the gaseous phase, however not based on the traditional Navier-Stokes equation. The fluid motion caused by the fluid granule elastic collision is determined based on the equation of state for fluids and their constitutive relation under the Hertzian contact theory, and the fluid motion caused by density difference is determined based on the Pascal principle and the speed equation of sound in the gaseous phase. GHM has given the physical properties of fluid and solid into consideration. There is a couple of symmetric vortex behind the cylinder, when the Reynolds number is between 5 and 40. When the Reynolds number is about 190, the couple of symmetric vortex is started breaking away from the cylinder. With the increase of Reynolds number, the flow behind the cylinder appears as different forms.