Characterization of inhomogeneous turbulence using the filter approach.
Wednesday, September 12, 2018
Variable density flows occur in physical systems including stably-stratified shear flows associated with oceanic overflows and in jets of one density fluid into another as in volcanic eruptions. An analysis approach for such systems is related to the simulation method known as Large Eddy Simulation (LES): by applying a spatial filter to a turbulent field such as velocity, one can divide up the flow into large and small scale components that pass, for example, energy between scales. Recently researchers have used this formalism to analyze turbulent flow by measuring the coupling terms in highly resolved DNS or in similar experiments. We present the application of the filtering approach to variable-density flows, taking two example systems. The first is an experiment on stably-stratified shear flow where a Boussinesq approximation is adequate. In the second experiment, there are order one variations in density for a buoyant jet of SF6 into co-flowing air.
Robert (Bob) Ecke is a Senior Scientist at Los Alamos National Laboratory (LANL). He is also a Laboratory Fellow, a position he has held since 1997. He served as Director of the Center for Nonlinear Studies at LANL 2004-2014, where he guided research on interdisciplinary science including quantitative biology, information science and technology, quantum information science, and non‐equilibrium statistical physics. He received his Ph.D. in Physics from the University of Washington in 1982. His work has revolved around laboratory experiments in hydrodynamic stability, dynamical systems, chaos, turbulence, and statistical physics. His research has spanned many applications, including thermal convection in superfluid helium mixtures, rotating convection and pattern formation, material dissolution and compositional convection, turbulent boundary layers and heat-transport scaling, spatio-temporal dynamics in pattern forming systems, 2D laboratory turbulence, turbulence in stratified flows, and statics/dynamics of granular materials. His current research interests include turbulence in atmospheres and oceans, fundamental studies of turbulence, and the properties of flowing granular materials.
Bob has served in numerous professional society positions, including Chair of the APS Group on Statistical and Nonlinear Physics, Editor for Chaos, and Divisional Associate Editor of PRE. Ecke won the Los Alamos Fellows Prize in 1991 and is a Fellow of both the APS and the AAAS.