Optimum design of micromixer for a non-Newtonian fluid by topology optimization

Improving the mixing performance is a crucial and widely concerned topic in microfluidic devices for low Reynolds numbers (Re). In this paper, the mixing unit as the design domain in a typical T-shape micromixer considering non-Newtonian fluid effects is investigated using topology optimization. The objective of topology optimization is to maximize the mixing quality under the prescribed pressure drop of the micromixer. Based on the optimized structures obtained by topology optimization, high-fidelity calculations are performed to eliminate the influence of the greyscale problem. For the Newtonian fluid, the optimized structure has better mixing performance than the reference structure with the same pressure drop. For the non-Newtonian fluid, crosscomparison is conducted to obtain the optimized structure. The results show that the mixing qualities of the 25-period mixing unit are 93.90% (Newtonian fluid, Re = 8) and 93.84% (non-Newtonian fluid, Re = 0.24), respectively.