Can energy-eddies of 100 meters size be understood from eddies of 1 centimeter size?
Department of Mechanical Engineering & Materials Science Seminar
Dr. Adrián Lozano-Durán
Center for Turbulence Research
Stanford University
Can energy-eddies of 100 meters size be understood from eddies of 1 centimeter size?
The answer is yes. Turbulent flows in the presence of bounding surfaces, as those occurring in oceanic and atmospheric currents, around vehicles, or inside pipes, may be apprehended as a collection of whirls or eddies. These eddies follow a regeneration cycle, i.e, existing eddies are seeds for the origin of new ones and so forth. Understanding this process is critical for the modeling and control of geophysical and industrial flows where a non-negligible fraction of the energy is dissipated by turbulence in the immediate vicinity of walls. In the present work, we examine the causal interactions among energy-containing eddies in wall-bounded turbulence by measuring how the knowledge of past states of the eddies reduces the uncertainty of future states. Our approach unveils, in a simple manner, that causality of energy-eddies at a given scale is essentially universal and independent of the eddy-size. This observation is accompanied by striking implications for control and modeling of turbulent flows. We show, using neural networks as an example, that novel eddy prediction techniques can be devised for the computationally more affordable smaller eddies, while still being a faithful approach applicable to larger eddies which are intractable even with the current state-of-the-art supercomputers.
Short Bio: Dr. Adrian Lozano-Duran received his PhD from the Technical University of Madrid in 2015 at the Computational Fluid Mechanics Lab. headed by Prof. Jiménez. His main research has focused on Computational Fluid Mechanics and the fundamental physics of wall-bounded turbulence. Currently, he is a Postdoctoral Fellow at the Center for Turbulence Research at Stanford University working on the fundamentals of wall turbulence, large-eddy simulation, and reduced-order-modeling.
Monday, February 25, 2019
2:30 – 3:30 pm
Location – Mason 107
Host: Professor Udo Schwarz