Numerical simulation of suspension transport in bifurcating and wavy channels

Abstract

This thesis deals with the numerical investigation of the shear-induced particle migration of neutrally buoyant suspensions in bifurcating channels and wavy channels via continuum via computational fluid dynamics (CFD) simulations. The CFD simulations based on continuum models such as diffusive flux model (DFM) and suspension balance model (SBM) have an advantage over the computationally intensive particle tracking simulations as they can be generalized for complex geometries. The suspension considered in our simulations was non-colloidal, and non-Brownian rigid particles in a stokes regime (Re <<1).Numerical simulations of monodispersed suspension in a 3D oblique bifurcating channel were performed to study the concentration and velocity profiles before and after bifurcation. Both DFM and SBM were considered in the simulations and compared quantitatively. The effect of bifurcation angle on the velocity, particle concentration, and partitioning of bulk flow and particles in the downstream branches has been carried out. The suspension fluid velocity profiles showed a marked difference over pure carrier fluid velocity profiles and greatly depends on the orientation of the geometry (bifurcation angle). After the bifurcation, the velocity and concentration profiles become asymmetric and degree of asymmetry depends on the bifurcation angle. As the bifurcation angle increases, the dividing streamline shifts towards the side branch and suspension shows slightly different behavior over pure carrier fluid. The partitioning of the particles does not follow the fluid partitioning. The findings of DFM and SBM were very similar.