An Immersed Boundary Direct Numerical Simulation Study of Wall Effects on the Dynamics of a Sphere Moving in Laminar Flows
This study applies an Immersed Boundary Direct Numerical Simulation (IB-DNS) to predict the dynamics of a rigid spherical body in the presence of a vertical wall at particle Reynolds numbers between 0.18 to 100. The wall effect causes an increase in drag coefficient that is stronger at lower Reynolds numbers and smaller particle-wall gaps. Wall effects have been presented with published analytical, experimental, and numerical correlations but much data is lacking for numerical studies over low to moderate Reynolds numbers over a wide range of wall gaps. Further, no studies have been attempted utilizing an IB-DNS approach.
The first goal of this research is to apply an IB-DNS method to develop drag correlations for particles translating parallel to a vertical wall in a quiescent fluid for Re 0.18 to 10 and wall gaps of 0.625 to 4. In doing so, this research validates theoretical, experimental, and numerical studies in a unified study and methodology over the range studied. The correlations presented can be used to predict the actual particle drag for near wall cases at Re=.18 to Re=10 where the wall effect is most significant. Secondly, this study numerically validates recent experimental studies of freely settling particles near a wall. Once validated, these studies are then extended numerically to investigate parameters not yet investigated such as particle angular velocity and effect of the initial release point. This research demonstrates the IB-DNS method being used to accurately predict particle dynamics in the presence of a wall.