Inertial separation of microparticles suspended in shear-thinning fluids

This study aims to investigate the inertial separation of microparticles suspended in a non-Newtonian Carreau fluid using a single-loop microdevice. Numerical simulations are performed for focusing of polystyrene microparticles with diameters of 5, 15, and 25 μm, power-law index n = 0.7 and n = 0.9, as well as relaxation time constant λ = 0.7, λ = 0.07, and λ = 0.007 s. The impact of these parameters on the trajectory of particles and particle separation rate is investigated. The results demonstrate that, compared with the Newtonian case, the shear-thinning effect leads to the center of the Dean vertices deviating from the symmetrical state and moving toward the outer wall of the microchannel. It can be concluded that the separation efficiency decreases by reducing the power-law index and relaxation time constant. It is revealed that the separation efficiency of 25-, 15-, and 5-μm particles is 100% when n = 0.7 and λ = 0.007 s.