Modelling and Simulation of 2D-flow Suspension Diffusioosmosis

Diffusioosmosis, also referred to as capillary osmosis, is the flow of a solution relative to a fixed object, where the flow is driven by solute concentration gradient. The solution considered here is an aqueous mixture containing colloids that flows in a channel and through an array of cylinders, representing a membrane. In this work we use an adaptation of the suspension balance model to investigate the influence of colloid – interface (Πic) interaction and colloid – colloid interactions (Πcc) on the diffusioosmosis of a colloidal suspension. The model describes both osmosis and Marangoni flow, depending on the attractive or repulsive nature of Πic. Further, Πcc dictates two important features of the flow. First, increasing the gradient of colloid concentration between the two channels by a factor of 10 increases the pressure drop by a factor of ~3.2 in the advection – osmosis equilibrium state. Second, including higher-order terms from the hard-sphere repulsion model (via the Carnahan-Starling equation of state) can increase colloid concentrations near the membrane by ~30%.