Investigation of slip boundary conditions in the T-shaped microchannel

Abstract

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 100μm×200μm, and its length was 1400μm. The transverse inlet channels were symmetric about the mixing channel, and their cross-section was 100μm×100μm, and the total length was 800μm. 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 70μm in the calculations. It was shown that the mixing can be controlled by hydrophobic coating.