Proposal Number: 0625452 Principal Investigator: Gupta, Nivedita R. Affiliation: University of New Hampshire Proposal Title: Elastic and Surfactant Effects on Drop Dynamics
Intellectual Merit:
The goal of this project is to advance the understanding of two phase viscoelastic flows with surfactant effects in confined domains. Rheologically-complex multiphase materials are encountered in a growing number of commercial applications, such as materials processing of polymer blends, enhanced oil recovery using polymer solutions, and DNA solutions in microfluidic devices. The stretching of polymer chains present in viscoelastic fluids causes large normal stresses to develop at strongly deforming interfaces affecting the dynamics of drops. Surface- active agents (surfactants) are often added to these systems as compatibilizers or emulsifiers. Surfactant molecules adsorbed at the interface can redistribute along the interface leading to a local reduction in surface tension. This may result in highly curved interfaces and reduced tangential velocities due to the induced Marangoni stresses. The interplay between the hydrodynamic timescales, the fluid relaxation timescales, and the surfactant transport timescales can be very complex. A limited number of numerical studies exist to date on the deformation and break up of viscoelastic drops in tubes and channels in the presence of surfactants. The major research objectives of this study are to: (1) identify parameters governing the drop shape and velocity for a drop translating in a tube or rectangular channel; (2) determine the effect of elastic stresses on the drop dynamics, and (3) determine the effect of mass transfer kinetics of surfactants on the deformation of drops.
Broader Impact:
In addition to advancing the field of interfacial phenomena with elastic and surfactant effects, this research will lead to a new elective course in the Chemical Engineering undergraduate/graduate curriculum on 'Interfacial Fluid Mechanics'. The course will draw material from the PI's own research and will provide the students with hands-on experience in her laboratory. The PI, being a woman engineer herself, will encourage the involvement of women and members of minority groups in her research and in the field of science and engineering in general.
