Professor Satwindar Sadhal
Professor of Aerospace & Mechanical Engineering and Ophthalmology
University of Southern California
Los Angeles, CA
Presentation Title: Physicochemical Hydrodynamics of Drops and Bubble with Surfactants
Abstract: The motion of drops and bubbles with the presence of surfactants and impurities has been a subject of considerable scientific interest for the past several decades ranging from the basic fluid dynamics and mass transfer to various engineering and scientific applications. It is known that low-solubility surfactants tend to accumulate at the interface, causing retardation of the motion of drops and bubbles. This phenomenon gives rise to concentration dependent interfacial stress leading to interesting fluid dynamics, both within drops and the exterior region.
In this lecture, the fundamental aspects of the interfacial dynamics will be discussed, and the analytical developments related to the effect on the convective transport of surfactants will be presented. Additionally, several practical applications of surfactants associated with bubble dynamics will be discussed. For example, surfactants are useful for the mitigation of gas embolism in blood vessels that can occur during surgical procedures. Surfactants can successfully lead to the reduction of wall shear in the blood vessels reducing the serious negative effects of the presence of bubbles. Another example is the enhancement of boiling heat transfer whereby surfactants, through reduction of interfacial tension, lead to increased bubble departure frequency and a reduction in departure size and thus an increased heat transfer rate. A similar effect also occurs with droplets impacting on heated surfaces where surfactants play a role in raising the Leidenfrost point.
Biography: Professor Sadhal received his PhD at Caltech in Engineering Science in 1978. He is a Professor of Aerospace & Mechanical Engineering and Ophthalmology at USC. He is the lead author of the book, Transport Phenomena with Drops and Bubbles. He has worked on NASA projects involving containerless processing using acoustic levitation techniques, and has also made fundamental contributions to nonlinear acoustics, particularly streaming phenomenon with liquid drops. His technical contributions include a large body of scientific of literature on fluid, thermal and material transport. He is a Fellow of ASME and the recipient of the 2007 James H. Potter Gold Medal and the 2019 Heat Transfer Memorial Award. His current activity includes ocular fluid dynamics and transport associated with drug delivery, transport and permeability properties of the vitreous humor and retina. His team has conducted research on intravitreal drug delivery in collaboration with the USC Roski Eye Institute for the last several years with funding from Allergan, Inc. and the National Eye Institute (NIH).