Numerical investigation of mixing performance in microchannel T-junction with wavy structure

Abstract

Mixing in chemical microreactors is a multi-scale processes as the transport mechanisms occur at different length scales. Since the small scale mixing depends mainly on molecular diffusion, a relatively long channel is necessary to achieve the desired mixing. To improve the mixing quality whilst keeping easy and simple manufacturing, an innovative design of microchannel T-junction with wavy structure is proposed to trigger secondary flow for enhanced chaotic mixing. To gain better understanding of the interplay of transport mechanism, we develop numerical model for micro-mixing in micro-channel T-junction with wavy structure; the model considers single phase mixing of laminar Newtonian miscible fluid and it solves for conservation of mass, momentum and species. To ensure robust and accurate solutions, several discretization methods and mesh sizes were tested and compared; while to ensure fidelity of the comparison of mixing performance, we introduce the performance index (PI) concept for the first time in micromixing area. The numerical results suggest that the mixing quality and PI improves significantly for microchannel T-junction with wavy structure, especially at higher Reynolds number. The performance enhancement is also seen for all range of Schmidt numbers, wavy frequencies and amplitudes considered, which shows potential for several practical applications.