VIRTUAL GRADUATE SEMINAR IN FLUID MECHANICS
Join online via Zoom: https://wse.zoom.us/j/435449376
Friday, September 11, 2020, 4:00 p.m. – 4:50 p.m. (EDT)
“A Peek into the Lagrangian Pair Dispersion in Turbulence at Infinite Reynolds Number”
Presented by SHIYONG TAN
(Adviser: Prof. Rui Ni)
Observing the Richardson-Obukhov cubic scaling law in experiments at large Reynolds number is challenging because it requires tracking particles for a long time before the finite view area starts to play a role. We approached the problem from a different direction by reducing the initial separation between two particles in a water tunnel equipped with a high-concentration particle tracking system. By following particles with almost two and half decades of time scales, we successfully observed the Richardson scaling for the initial separation at about 3eta. The dependence of this scaling exponent versus different initial separation will be discussed, and this dependence provides a new way to study the dispersion dynamics and intermittency at finite and infinite Reynolds number.
“Vortex-Induced Vibration: A Misnomer?”
Presented by KARTHIK MENON
(Adviser: Prof. Rajat Mittal)
The focus of this work is to uncover the physical mechanisms that initiate and sustain flow-induced vibration of cylinders. We demonstrate the use of a rigorous formulation that allows us to partition the flow-induced force and work done on an immersed body into specific physically relevant components, as well as distinct spatial regions in the flow. This allows us to directly quantify the influence of each of these forcing mechanisms, and also the influence of distinct flow structures, in driving flow-induced vibrations. The analysis suggests that vortex shedding in the wake might not be the primary driver of so-called “vortex-induced vibrations.