Experiments of Cylinder Drag through Density-Matching Particle-Fluid Mixture and SPH Simulation

Abstract

A series of cylinder drag experiments were conducted using the density-matching Poly-Styrene Beads particle-fluids mixture to study the flow characteristics of liquefied sands. PIV technique was used to visualize the velocity fields around the moving cylinder. SPH (Smoothed Particle Hydrodynamics) simulations were also conducted to compare with the experimental results. Experiments results show that the solid fraction of 0.555 is quite important in this particle fluid mixture because the drag force exerted on the cylinder increases sharply with the solid fraction if it is greater than this value. This value coincides with the random loose packing density of mono-disperse spheres. PIV analysis shows that the velocity fields are quite localized around the cylinder, and the localized zone is expanded more in the moving direction than in the perpendicular direction. On the other hand, it turned out that the SPH simulations with a simple viscous fluid model cannot reproduce the similar velocity field, which indicates this particle-fluid mixture cannot be regarded as viscous fluid.