Seminar: Kinetic fluctuations and their role in laminar-turbulent transition of boundary layer flows

Receptivity of high-speed boundary layers in calorically perfect gas is considered within the framework of fluctuating hydrodynamics introduced by Landau and Lifshitz (1957). It is assumed that kinetic fluctuations (KF) manifest themselves in the governing equations through “stochastic forcing” by a random stress tensor and by a random heat flux. The stochastic forcing generates unstable modes leading to laminar-turbulent transition in boundary layers. Although the initial amplitudes of the unstable modes generated by kinetic fluctuations are small, they go through a significant amplification and may lead to laminar-turbulent transition. The results open up an opportunity to estimate the upper bound of transition Reynolds number established by Mother Nature.  This is a very new topic in the modern hydrodynamic stability theory. The presentation will be aimed at students to show how fundamentals in physics, thermodynamics, and fluid mechanics may lead to new technical applications including design of hypersonic vehicles.

About the Speaker

Anatoli Tumin is a Professor of Aerospace and Mechanical Engineering and a Member of the Applied Mathematics program at the University of Arizona. He received his M. S. in physics and applied mathematics from Novosibirsk State University (1972) and his Ph.D. and Dr. Sci. in physics and mathematics from the Moscow Institute of Physics and Technology (MIPT) in 1975 and 1987, respectively. In 1975, he joined the faculty of the Physics Department at MIPT. In 1982, he was employed by the Scientific-Industrial Design Bureau “Molniya,” where he participated (as Lead Designer and Head of Sector) in the design of the Soviet Space Shuttle “Buran.” His responsibilities included prediction of laminar-turbulent transition and nonequilibrium heat transfer in reentry flight, specification of tolerances for elements of thermoprotection system, and other aspects of aerothermodynamics relevant to the design of hypersonic vehicles. In 1992, he joined the faculty of Tel-Aviv University. In 2000, he joined the faculty of the University of Arizona. His current research interests include theoretical and computational studies of stability, laminar-turbulent transition, and flow control in high-speed flows including real gas effects.

Hosted by Professor Datta Gaitonde