Computational Analysis of Passive Mixing in T-Micromixer with Non-Newtonian Blood

Micromixers are an essential integral part of the Lab-on-chip (LOC) devices which carry importance in the domain of chemical, biomedical and biochemical applications. The flow and mixing behavior of fluid changes drastically when the length size is scaled down to the order of microns due to the dominance of viscous forces as compared to the macroscale where the inertial forces influence the flow. The present study examines the flow characteristics and passive mixing behavior in a simple T-micromixer with Newtonian fluid water and Non-Newtonian blood having an aspect ratio (width/height of the channel) 2 using computational fluid dynamics (CFD) for a wide range of Reynolds number (2 ≤ Re ≤320) for water and the corresponding mass flow rates of blood. The Carreau-Yasuda model is employed to model the Non-Newtonian rheology of blood used in the simulation, whereas water is considered to be Newtonian fluid possessing constant viscosity. The flow and mixing behavioris different for water and blood. It is seen that initially, mixing efficiency for water decreases with an increase in the Reynolds however, an increase in mixing performance is observed with a further increase of Reynolds number. In contrary to the Newtonian fluid water, a continuous decreasing trend in the mixing efficiency is visible with an increase in the mass flow rate for blood analysis. The maximum mixing efficiency of the micromixer with water is 31.9%, whereas for blood it is 34.5%. Finally, the pressure drop in the mixer between inlets and outlet are studied for both blood and water as it is an important parameter linked to the requirements of pumping power.