AE Seminar

Computational and Theoretical Methods for 
Characterizing Turbulence in Realistic Parameter Regimes

ft. 

Sualeh Khurshid

Assistant Research Professor | School of Mechanical, Aerospace & Manufacturing | University of Connecticut

Thursday, March 6
11 a.m. - 12 p.m.
Guggenheim 442

About the Seminar: 
Turbulence is ubiquitous in natural and engineering systems. It can suppress energy loss in fusion reactors, affects stellar formation, has first order effects on processes critically important to society such as mixing of chemicals and pollutants in the atmosphere and oceans, climate dynamics and high-speed flight. It is therefore critically important to develop fundamental understanding of turbulent processes to improve predictive capabilities of turbulent fluid systems. An important hurdle in characterizing turbulent flows is the presence of extreme events, e.g. in dissipation, velocity gradients etc. These events are often very high-dimensional in nature and require large degrees of freedom/grid points to resolve accurately in simulations. The extreme events become stronger at high Reynolds number (Re, parameter characterizing the strength of turbulence) that are characteristic of realistic flows. Therefore, the focus of much of turbulence research has been to simulate very high-Re flows. This is a challenging computational task as the computational workload can grow as steeply as the fourth power of Reynolds number. Direct simulations of complex turbulent flows at realistic conditions currently (and in the near term) remain elusive on the largest supercomputers. In this talk, we present methods that enable understanding high-Re turbulence using computational resources available today. We will show that features of canonical high-Re turbulence can be studied at finite and small values of Re and they are predictive of theoretical infinite-Re limit. For complex flows, we will describe a new computational technique that enables simulation of high-Re flows on modest computing resources with DNS level accuracy for small-scales. A primary focus is on the universality of small-scales and the scaling of extreme events. The consequences of these fundamental insights on modeling approaches, phenomenological and data-driven, in complex turbulent flows will also be discussed. The work also provides a new perspective on computational study of complex systems at very high values of dynamically relevant parameters.

About the Speaker: 
Sualeh Khurshid is an Assistant Research Professor in the School of Mechanical, Aerospace & Manufacturing at University of Connecticut. His research is focused on understanding fundamental characteristics of complex turbulent flows in various regimes using direct numerical simulations and theory. His work includes developing high performance simulation codes and appropriate numerical methods to guide the development of reduced order models using phenomenological and data-driven methods. Previously, he was a Computing Innovation Fellow and Postdoctoral Associate in Mechanical Engineering at Massachusetts Institute of Technology. He completed undergraduate programs in Aerospace Engineering and Physics. He earned his Ph.D. in Aerospace Engineering in 2021 under the guidance of Prof. Diego Donzis and collaborating with Prof. K.R. Sreenivasan at Texas A&M University. He is a recipient of NSF-CRA Computing Innovation Fellowship, Distinguished Graduate Student Award at Texas A&M University and Hagler Institute HEEP fellowship.