Efficient mixing in microfluidic systems remains a significant challenge, particularly for non-Newtonian fluids and deformable microchannels, where fluid–structure interaction (FSI) is crucial. Existing studies often overlook the effects of wall flexibility, particularly when hyperelastic materials are involved. This study aims to numerically investigate the mixing process in a micromixer with a flexible channel wall and analyze the impact of this flexibility on mixing efficiency. Utilizing the Navier-Stokes equations and the continuity equation for fluid dynamics, alongside the convection-diffusion equation to derive the concentration profile, we solved the solid-body equations through a fully coupled two-way Fluid-Structure Interaction (FSI) using the Arbitrary Lagrangian-Eulerian (ALE) method. The power-law fluid model and the two-parameter hyper-elastic Mooney-Rivlin model were employed to characterize the channel wall. Parametric analyses were conducted using COMSOL Multiphysics 6.2, exploring a Peclet number range of 2000 to 6000, power-law indices from 0.6 to 1.4, and dimensionless wall thicknesses of 0, 1, 1.5, and 2. The results revealed a significant increase in mixing efficiency, reaching 60% when the channel wall was configured as flexible for a power-law index of 1.4 at a Peclet number of 6,000. Additionally, the pressure drop was notably reduced to approximately one-third of its original value under the same conditions, highlighting the advantages of employing flexible walls in microfluidic applications.
Faradonbeh et al. (Wed,) studied this question.