“Soft Boundaries in Two-Phase Flows”

Emilie Dressaire

Assistant Professor

Mechanical Engineering

University of California, Santa Barbara

Wednesday, June 1, 2022

37-124 Eng. IV
Time: 11:00 am – 12:00 pm

 Abstract: Fluid flows can generate stresses sufficiently large to destabilize interfaces, deform and fracture solid substrates. While the interactions between fluid flow and surface deformation are typically studied with a single fluid, two-phase flows are common in agricultural, manufacturing, and energy processes. The two immiscible liquids are separated by an interface, which results in capillary stresses. In this talk, I will present two recent studies on multiphase flows confined by deformable, soft boundaries. First, we will revisit the classical displacement flow problem in a growing fracture. The successive injection of two fluids in a brittle elastic material drives the formation and growth of a penny-shape fracture. Using model experiments, we characterize the fracture dynamics. The viscous dissipation in the fluid, the elastic stresses and toughness of the matrix control the flow in the fluid-filled fracture. We demonstrate that the role of the two fluids depends on the regime of fracture propagation, fluid-controlled vs matrix-controlled.  Then, I will present results on the atomization of oil in water emulsions. We study the impact of a drop of emulsion on a small target which lead to the formation and atomization of a liquid sheet. Here the dispersed phase is confined between air/liquid interfaces. The oil droplets modify the dynamics of an aqueous liquid sheet and its break-up into droplets. As the viscosity of the oil phase decreases, the liquid sheet becomes more unstable, and holes become primarily responsible for the atomization of the sheet. These studies illustrate the complex couplings between two-phase flows and substrate deformation.

Biosketch: Emilie Dressaire received a B.S. in Engineering from ESPCI, France, in 2005, and a Ph.D. in Mechanical Engineering from Harvard University in 2009. She joined the Mechanical and Aerospace Engineering Department at NYU Tandon School of Engineering in 2014. She is now a faculty member in the Department of Mechanical Engineering at UCSB. She served as a Member-at-Large on the Executive Committee of APS Division of Fluid Dynamics from 2018-2021. Her research interests are centered around small scale fluid mechanics and soft matter physics, specifically focusing on poro-elasticity in biological systems and for bio engineered solutions.

For more information, please contact Prof. Taira at ktaira@seas.ucla.edu

All faculty, students, and guests are welcome to this event. (Refreshments will be served.)