Investigation of slip boundary conditions in the T-shaped microchannel

摘要

Flow regimes and mixing performance in a T-type micromixer at high Reynolds numbers were studied by numerical solution of the Navier-Stokes equations. The Reynolds number was varied from 1 to 1000. The cross section of the mixing channel was 100 μm × 200 μm, and its length was 1400 μm. The transverse inlet channels were symmetric about the mixing channel, and their cross-section was 100 μm × 100 μm, and the total length was 800 μm. Five different flow regimes were identified: (ⅰ) stationary vortex-free flow (Re ＜ 5); (ⅱ) stationary symmetric vortex flow with two horseshoe vortices (5 ＜ Re ＜ 150); (ⅲ) stationary asymmetric vortex flow (150 ＜ Re ＜ 240); (ⅳ) non-stationary periodic flow (240 ＜ Re ＜ 400); and (ⅴ) stochastic flow (Re ＞ 400). Maximum mixing efficiency is obtained for nonstationary asymmetric vortex flow. In this case, an S-shaped vortex structure is formed in the flow field. The effect of the slip conditions on the flow pattern and mixing efficiency is studied. The slip length varied from 1 to 70 μm in the calculations. It was shown that the mixing can be controlled by hydrophobic coating.