Numerical Study of the Velocity Profiles in an Incompressible Laminar Flow With Particles Between Two Parallel Plates

Abstract

Abstract This paper presents a two-dimensional numerical study of the velocity profiles of an incompressible laminar flow with particles between two parallel plates. The model is developed using COMSOL Multiphysics 6.0 software based on the finite element method. A laminar water flow is used for the continuous phase, and fluid-particle interaction is established through a bidirectional coupling under a temporal configuration. This study aims at analyzing the fluid-particle interaction dependency on parameters such as the Stokes number (St), the volumetric fraction (αp), and the relative size of particles (RSp), and how varying them affects the development of the boundary layer with particles. Two types of velocity profile graphs are presented, one along lines parallel to the plates and another along lines perpendicular to the plates, both to study how the velocity is affected while varying the parameters mentioned before. Graphs of the velocity difference cases of fluid with particles to the case of fluid alone were developed. Three zones are observed: an acceleration zone, in which velocity increases up to a maximum point (peak); a transition zone, where it starts to decrease and progressively stabilize; and finally, a stable zone, where the fluid flow with particles eventually has the same behavior as the fluid alone flow as the boundary layer with particles develops completely and the interaction of particles with the fluid diminishes. It was observed that particles interfere with the development of the boundary layer, and that the interference increases proportionally with the volumetric fraction of particles (αp), while inversely proportional with the relative particle size (RSp). It was found that the volumetric fraction (αp) and the relative particle size (RSp) have a linear proportionality with fluid velocity difference. It is also shown that as the Stokes number increases, particles react more slowly to the fluid flow, further delaying the boundary layer development. In the velocity difference graph and peak was observed and its location in the channel tends to shift as the Stokes number varies. This peak shift was not observed when varying the volume fractions and/or relative particle size.