Numerical studies of colloidal particle deposition in microchannels

Flow in microfluidic devices has many practical applications ranging from lab-on-a-chip technology, development of inkjet print heads, micro propulsion etc. Most microfluidic systems have two phase flow systems in which colloidal dispersions are commonly used. This investigation focuses on describing the deposition kinetics of colloidal particles dispersed in an electrolyte solution in a pressure driven flow through a parallel plate micro channel. Deposition studies have been quantified by developing an unsteady state mass conservation equation. The model takes into account hydrodynamic interactions, Van der Waals forces, electric double layer forces and gravitational forces. The effect of concentration of particles and the presence of wall on the effective diffusivities has also been incorporated in the model. A non-penetration boundary condition has been applied at the walls. The resulting unsteady state two dimensional differential equation in space has been discretised and integrated further using gears algorithm which has been proven to be highly effective for these kind of stiff systems. The particle deposition has been studied by performing extensive numerical simulations quantifying deposition in terms of dimensionless particle concentration. The dependencies with respect to grid resolution, Reynolds number, electrolyte concentration, particle diameter etc. has been investigated.