Effect of shear rate and flow rates ratio on non-Newtonian droplet formation in a T-junction microfluidic system

Abstract

Mono-dispersed phase non-Newtonian droplet generation has been carried out in a T junction microchannel using the level set method in this current frame of work. The simulations for various shear rate values ( 10-4 ≤ 𝛾̇ ≤ 105) were carried out. Non-Newtonian is assumed to be carried out as dispersed phase fluid, whereas continuous phase is taken as a Newtonian fluid. The transient flow in the microchannel has revealed the dynamics of droplet formation of the dispersed phase with shear-dependent fluids. The flow regimes have been classified into droplet and non-droplet zones using the power-law index (𝑛) for different shear values. The flow regime classification thereby establishes the possibility of drop- let formation for certain combinations of shear rate and power-law index. It is observed that there is a droplet formation at lower values of flowrate ratio (𝑄𝑟 < 1) for shear-thinning fluids for a range of the shear rate. However, the flow is becoming parallel at a higher flowrate ratio (𝑄𝑟 > 1) values. For a particular value of flowrate ratio and shear rate, there is a droplet generation for shear-thin- ning fluids, and whereas the flow is becoming parallel in the case of shear thickening fluids.