Effect of inlet conditions on the engulfment pattern in a T-shaped micro-mixer

The effect of the inlet flow conditions on the degree of mixing in a T-shaped micro-mixer is investigated numerically. Specifically, it is observed that if the flows at the micro-mixer confluence are not fully developed, engulfment occurs at larger Reynolds number, with a different flow pattern and with much lower mixing efficiencies, compared with the case where the inlet flows are fully developed. Thus, for a given micro-mixer geometry, two different engulfment flows may be found as the Reynolds number is increased, corresponding to successive symmetry breaking processes. This work highlights also the importance of both a fine discretization of the micro-mixer as well as of suited convergence criteria for the setting of the numerical simulations.

► Engulfment at larger Re if the inlet flows are not fully developed.
► Multiple engulfment patterns (S- and C-shaped) depending on Re.
► Fluctuating flow for Re above the engulfment for developed inflows.
► Unstable numerical solutions for residuals of all equations below 10−7.