Simulations of viscoelastic droplet deformation through a microfluidic contraction

A modified Volume-of-Fluid numerical method is developed to predict the transient deformation of a viscoelastic drop surrounded by a more viscous Newtonian liquid passing through an axisymmetric microfluidic contraction. Viscoelastic effects are represented using an Oldroyd-B rheological model and can be generated in practice by the addition of small amounts of polymer. The numerical method is tested against experimental observations of viscoelastic drops forming at nozzles. We show that these simulations reliably reproduce flow and drop deformation. Predictions of drop shape and elastic extension are then presented and discussed for drop motion through a microfluidic contraction, and these results are compared against results for an equivalent Newtonian only system