Numerical Simulation of the Cleaning Process of Microchannel by an External Flow

Abstract

The paper is devoted to the study of the process of cleaning a microchannel contaminated by impurity particles settling on its walls. The most common reason of microchannel clogging is the sorption of impurity particles by pore walls or “physical sorption”. This paper describes the problem of drift of solid non-interacting particles in a microchannel, which can stick to its walls under the action of the van der Waals forces and break away from the wall due to thermal noise and viscous stresses arising from the flow. The pressure drop is given between the channel inlet and outlet. At the initial moment of time, the channel walls are contaminated with adhered particles, i.e. the walls are uneven, which affects the formation of the flow structure through the channel. Over time, under the action of viscous stresses and thermal noise, the particles break away from the channel walls, causing its cleaning. The interaction of the detached particles with the flow is taken into account in the approximation of the laminar flow regime. In addition, the model takes into account random particle motion caused by diffusion. The problem is solved numerically within the framework of the random walk model. The evolution of the liquid flow in the channel during its cleaning is obtained: stream function, pressure, and vorticity fields. It is demonstrated that three cleaning scenarios can be observed: no cleaning, slow cleaning, and fast cleaning. To control the cleaning scenario the modulation of the pressure drop at the channel borders is investigated. It is shown that resonance phenomena can be observed. The dependencies of cleaning time on the modulation amplitude and frequency is obtained and studied. It is shown that changing the modulation parameters leads to a significant change in the cleaning time and helps control the cleaning process.