NUMERICAL SIMULATION OF INLINE ARRANGEMENT OF SPHEROID PARTICLES IN DIFFERENT ORIENTATIONS

摘要

The understanding of relative motion between particles of non-spherical shapes is of critical importance in many engineering and natural applications. The flow analysis and later explanation of physics can be used for designing and modification of industrial equipment. In this study, computational fluid dynamics is used to numerically solve two-dimensional steady fluid flow for two tandem spheroid particles. The parameters which are varied in simulations are combined effect of Reynolds number (Re), axis ratio (e), inter particle distance (S), size ratio (d2/dl) and particle orientation (a) on the flow and drag force for tandem spheroid particles. For reliability of results, domain and grid independence studies are done before performing the actual simulations. Furthermore, simulations results are also benchmarked with the available literature results and good agreement is observed. It is observed in simulations that the drag increases with the increase in size ratio. Drag force is maximum for oblate particles for an axis ratio e=0.5 and larger inter-particle distance. For trailing prolate particles, the small inter-particle distance induces suction or negative drag. Furthermore, the negative drag on prolate particles at smaller inter-particle distance S=2 increase with the increase in size ratio d2/dl from 0.5 to 0.75 and negatively affects the collective drag (Cdl+Cd2). At Re=50, the trailing particle drag Cd2 is independent with the orientation angle. The effect of orientation of leading particles is important for Re=100 & 150. At the end of paper, the physics behind the affecting parameters on drag force is explained using inter-particle wakes and fluid structures.