Fluid Dynamics, Microfluidics

Predicting two-phase flow of Newtonian fluids is important in a variety of applications such as materials, polymer, and food processing, pharmaceuticals, and microfluidics. The interface between two fluid phases is often characterized by a single property, the interfacial tension. Variation of interfacial tension along an interface leads to tangential stresses that are known as Marangoni stresses. Temperature gradient or a gradient in concentration of surface-active agents (surfactants) along the interface leads to surface tension variation along the interface. Furthermore, if the bulk fluids exhibit viscoelasticity, they can store energy to some extent and display partial recovery upon removal of stress. The focus of this research is to understand the fundamental issues of how surface tension gradients affect free surface flows, how surfactants can be added to control flows, and how elasticity in the bulk phase changes the deformation and break up of a dispersed fluid phase.