DATE:                         5.9.24 

TIME:                          4:00 pm

LOCATION:              31-370

SPEAKER:                Vaishnavi Ramaswamy, Graduate Student, Hypersonics Research Laboratory

TOPIC:                       On Boundary Layer Stability Problems: Impact of Thermochemical Nonequilibrium & New Spectral Methods

ABSTRACT:

Boundary layer transition is the result of a complex laminar instability process [Reynolds] and is associated with large changes in skin friction and heating. An accurate transition prediction criterion is necessary for better and less conservative design of aerodynamic vehicles. Linear stability theory and parabolic stability equations provide a physics-based approach to model the amplification of boundary layer instabilities that ultimately result in transition. This seminar focuses on two research areas associated with this topic. The first area of focus is the impact of real gas effects seen in hypersonic flight on boundary layer stability. At the high temperatures associated with hypersonic flight, it becomes necessary to consider the effects caused by excitation of vibrational modes of gas molecules, and possible chemical dissociation of air species. Thermochemical nonequilibrium alters the mean laminar boundary layer flow and is also found to have a stabilizing effect on boundary layer disturbances. The second area of focus is a new spectral scheme available to solve boundary layer stability problems. The extension of stability theory to increasingly complex flows and geometries has added to the computational cost and time required to accurately solve these problems using existing numerical schemes. Therefore, it is useful to develop, implement, and test new numerical schemes that may be better suited to stability computations. Towards this end, we test a new spectral coefficient scheme, the US method [Olver and Townsend (2013)], to solve simple boundary layer stability problems in order to analyze possible improvements in computational efficiency and accuracy. 

BIO:

Ms. Vaishnavi Ramaswamy is a graduate student in MIT AeroAstro, working under the guidance of Dr. Wesley L. Harris in the Hypersonics Research Laboratory. Following her undergraduate education in India, Vaishnavi completed her Master’s from the Gas Turbine Laboratory in 2020. Her current research focuses on understanding the impact of thermochemical nonequilibrium on hypersonic boundary layer transition, and computational methods available to solve boundary layer stability problems.