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

TL;DR

This study numerically simulates the cleaning process of a contaminated microchannel by modeling particle detachment and flow dynamics, revealing how flow modulation can optimize cleaning time through resonance effects.

Contribution

It introduces a stochastic numerical model for microchannel cleaning, incorporating particle-wall interactions, thermal noise, and flow modulation effects, which was not previously addressed in detail.

Findings

Flow fields during cleaning are characterized and visualized.

Cleaning time can be controlled via flow modulation parameters.

Resonance phenomena significantly influence cleaning efficiency.

Abstract

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 Stokes approximation. 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. The dependencies of the volume occupied by settled particles, the flow rate through the channel and the channel gap on time are determined for different values of the interaction force between particles and channel wall. The estimations of the channel cleaning time are obtained and discussed. The possibility of control the cleaning process by the modulation of liquid flux through the channel 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.