Department Seminar of Evgeny Mogilevsky- Nonlinear waves at free surfaces of viscous liquids and within stratified interfaces
Nonlinear waves at free surfaces of viscous liquids and within stratified interfaces
Monday January 13th at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Abstract:
Modelling mass and energy exchange between fluids often involves solving free boundary problems, where the computational domain is unknown a priori, and the fluid interface must be determined during the solution process. These interfaces can exhibit instability, leading to the formation of propagating or standing waves. This lecture will explore two problems demonstrating different wave patterns in dispersive and non-dispersive systems with viscous liquids.
The first problem focuses on the modelling of a circular hydraulic jump, which occurs when a liquid jet hits a plane and spreads symmetrically as a thin, fast-flowing film. This phenomenon is relevant for numerous applications involving heat and mass exchange, coating technologies being important examples. Circular hydraulic jump also serves as a laboratory model for astrophysical phenomena where the governing equations resemble those used in shallow-water theory. Several approaches to describe and control this flow will be discussed, including the effect of external body forces on the evolution of the jump.
The second problem examines resonant standing waves at the interface between two deep fluid layers (the liquid-gas boundary and the mixed layer between two liquids with slightly different densities are considered). The waves are generated by a small vertically oscillating body, with the forcing frequency being slightly different from the system's natural eigenfrequencies. A model that simplifies the system to a finite number of degrees of freedom will be presented, predicting how detuning from the dispersion relation leads to a superposition of multiple spatial modes. The effects of stratification within the mixed layer will also be explored, with the identification of localized internal waves.
Bio:
Evgeny Mogilevskiy earned his M.Sc. in Mechanics (with honors) in 2005 and a PhD in Fluid Mechanics in 2009 from the Lomonosov Moscow State University. After a postdoctoral fellowship at the University of Leuven in Belgium in 2014 he returned to the Moscow University as a faculty member at the Faculty of Mechanics and Mathematics. There, he led a research group focused on the investigation of free-surface viscous flows, their stability, and wavy flow regimes. In 2022, he repatriated to Israel, where, after a three-month appointment as a visiting scientist at the Weizmann Institute of Science, he joined the School of Mechanical Engineering at Tel Aviv University as a researcher. The lecture presents an overview of research carried out at both Moscow and Tel Aviv Universities.
