Numerical simulation of particle segregation in a bidisperse suspension

We study, by means of numerical simulation, the behaviour of a colloidal suspension placed between two concentric, rotating cylinders (cylindrical Couette flow). Particles in the suspension are monodisperse and spherical. The simulation technique is the Stokesian dynamic method (Brady et al.). We are interested in a layer of fluid within a transverse section of the cylinders. Particles interact hydrodynamicaly each other and with the device's walls. They are expected to migrate from high to low shear regions, i.e. they move towards the outer cylinder. The resulting concentration profile agrees well with experimental (Philips et al.) and theoritical (Leighton and Actives) results. We also simulate the evolution of a suspension of particles with two different sizes in order to study the effect of polydispersity and establish concentration profiles, velocity profiles, and evolution of viscosity. Our aim is the understanding of migration mechanisms.