Effect of Viscoelasticity on Drop Deformation in 5:1:5 Contraction/Expansion Micro-Channel Flow

We implemented a finite element-front tracking method (FE-FTM) to understand the drop dynamics in microfluidic applications. We investigated the effect of viscoelasticity of both drop and medium. The Oldroyd-B model was used for viscoelastic fluid, and DEVSS-G/SUPG/Matrix logarithm were applied to improve numerical stability. We applied the algorithm to a drop deformation problem in 5:1:5 planar contractionnarrow channelexpansion flow. One of our goals is to propose the strategy to control the drop shape by exploring the effect of viscoelasticity of drop and medium. Here, we studied three different viscosity ratios between drop and medium by setting the ratio as 100 (more viscous drop), 1 and 0.01 (more viscous medium). In Newtonian fluids, the effects of drop size and capillary number (Ca) were investigated to get physical insights on drop deformation. As for fluid elasticity, the effect of Deborah number (De) was especially enhanced in more viscous drop case, while the effect was insignificant in other cases. The present study would be helpful to investigate viscoelastic effects on drop dynamics in microfluidics.