271903 Dynamics and Patterning of Complex Fluids with Energy and Environmental Applications
Higher-order fluidic patterning in complex fluids can be engineered for critical contributions in energy and environmental applications, from energy savings for large scale fluid transportation, to improved thermodynamic treatment in climate modeling, to enhanced particulate removal in industrial waste water processing. The patterning used for these applications can be observed in many complex solutions, on many scales, and are induced by such phenomenon as:
1. Viscoelastic effects seen with flow of polymeric solutions in curved streamlines
2. Thermalchemical effects seen in phase partitioning in atmospheric aerosols
3. Electrohydrodynamic effects seen in aggregate formation in colloidal suspensions
My research interests include the study of dynamics, bifurcations, and patterning observed with complex and responsive fluids, using experimental techniques, phenomenological scaling, and rigorous analytic mathematical modeling. Coming from a multi-disciplinary research background, I anticipate establishing a future research program for the study of dynamics and patterning of complex fluids, with the end goal of application-orientated tuning of the fluid behavior and properties.
I completed my Ph.D. in Chemical Engineering at the University of California, Berkeley in May 2009 while working with Professor Susan J. Muller. My doctoral research effort primarily focused on flow instabilities with complex (usually viscoelastic) solutions. The research effort aided in quantitative understanding and optimization of the polymer-induced turbulent drag reduction mechanism, a phenomenon that leads to significant energy savings for large scale fluid transportation. We studied the effects of polymeric additives in Taylor-Couette (TC) flow (flow between concentric, rotating cylinders), rather than in pipe flow, where the flow field transitions directly from laminar to turbulent flow with increasing Reynolds number. In TC flow, as the angular velocities of the inner and outer cylinders are varied, a rich cascade of distinct steady flow patterns, of varied complexity, can be accessed between unidirectional shear flow and fully developed turbulent flow. The use of complex, yet well-characterized, three-dimensional hydrodynamic patterning available in Newtonian TC flow as the background flow field allowed us to probe the effect of the polymeric drag reducing agent on isolated flow features and instability types. The stability planes and equilibrium flow states experimentally established in my PhD thesis, resulting from both centrifugal (inertial) and elastic (polymeric) forces, as well as the phenomenologic scaling models developed for both Newtonian and non-Newtonian fluids in TC geometries, elucidated the role of viscoelasticity in polymer-induced turbulent drag reduction.
Currently, I am a NSF-AGS postdoctoral research fellow at the University of California, Davis, working with Professors Anthony S. Wexler and Simon L. Clegg (Air Quality Research Center) and Professor William D. Ristenpart (Chemical Engineering). My postdoctoral research effort primarily focuses on thermodynamic and electrohydrodynamic properties of multi-component electrolyte containing solutions and aerosols. At the Air Quality Research Center, my work has integrated multilayer adsorption isotherms from gas and solid chemistry, and hydration shell theory and electrostatics from solution chemistry, to form an improved statistical thermodynamic treatment of the Gibbs energy, solvent and solute activity, solute concentration and surface tension for complex solutions and atmospherically relevant aerosols. The resultant thermodynamic model yields unprecedented agreement between the solute concentration and osmotic coefficients for solutions over the entire solute concentration range. Understanding the thermal and chemical forces on the stability of phase partitioning and both the molecular- and micro-scale patterning in atmospheric aerosols is essential for the exact thermodynamic predictions required for accurate climate modeling. Simultaneously, in the department of Chemical Engineering, I have been experimentally investigating colloidal aggregation and patterning, through electrohydrodynamic (EHD) manipulation. Colloidal aggregation through EHD flow has important energy-saving implications for use of electric fields for large-scale separation processes involving suspended particles.
In addition to being passionate about understanding and tuning complex fluids, I am also passionate about teaching and mentoring graduate and undergraduate students. As a faculty member, I anticipate using research as a teaching opportunity, in the classroom, in the laboratory, and in the broader community.