Hydrodynamics study of the flow past a cylinder with fine suspensions and evaluation of micropolar parameters

Abstract

The fluid in nature or engineering application usually contains fine suspensions, which differs the hydrodynamic properties from those of the pure fluid. To investigate the effect of the suspensions and evaluate micropolar parameters, micropolar fluids model and classical fluid-particle coupling model are adopted in the simulation of the flow past a cylinder. In this study, the program for the micropolar fluids was implemented based on OpenFOAM, and its correctness was validated comparing to the analytical solution of the micropolar Poiseuille flow. Then, flow behaviors involving the variation of the vorticity, microrotation and drag force were analyzed under different micropolar parameter N/Ls and Reynolds numbers. Last, coupling results of the classical fluid with discrete particles were presented to establish the relationship between the suspensions volume fraction and the micropolar parameter N/L. The results show that the drag force on a cylinder decreases with the increase of the micropolar parameter N/L (when N/L equals to zero, it represents the classical fluid.) and the increase of the Reynolds number augments the value of the microrotation. In addition, a quadratic function relationship between the suspensions volume fraction and the micropolar parameter N/L is established under certain conditions.