Dynamics of settling disks in a cross-flow

Abstract

Physical properties of rocks depend strongly on its grain packing which is determined by the natural process involving fluid-structure interaction during deposition. Here, we address the dynamics of settling solids with different sizes in a cross-flow numerically. This is an important aspect in rock formation process. Computational fluid-structure interaction usually involves the use of body-conformed grid. For the case of solid moving in a viscous fluid, the body-conformed grid has to be reconstructed in every time iteration which can be time consuming. The so-called Immersed Boundary method can be used to eliminate this grid reconstruction process. In this study, we use the couple of Immersed Boundary and Lattice Boltzmann Method (usually termed as IBLBM). In lattice Boltzmann, one does not require solving Poisson equation for pressure and a computation of intermediate field as in the usual fractional step procedure since velocity and pressure field can be obtained from the locally solved distribution function. These advantages make IBLBM can be easily employed. In this study, we perform simulations on the dynamics of a cluster of disks with two different values of diameter in a cross-flow. We compute the velocity distribution of the disks to study the sedimentation dynamics and we compare the results with a sedimentation process in a quiescent fluid. For the solid-fluid density ratio of 5 and incoming flow Reynolds number of 12, the velocity distribution is close to the normal distribution as also observed in the case of sedimentation in quiescent fluid.