Past Event: Oden Institute Seminar

Description of Hypersonic Effects on Wall Turbulence

M. Pino Martín, Professor, Aerospace Engineering Department and the University of Maryland Institute

Abstract

Enabling high fidelity simulations of entry and re-entry turbulent flow environments requires the generalization of scaling laws and new fundamental understanding describing the interaction of turbulence with shock waves, finite-rate reactions, surface catalysis and ablation, and radiation. Direct numerical simulations (DNS) provide detailed data to study aspects of wall turbulence, ranging from statistical scaling to the existence and characterization of the structure of wall turbulence. In Martín (J. Fluid Mech. 2007), we validated DNS for subsonic to hypersonic wall bounded turbulence. The simulations rely on robust dynamic shock capturing, minimal dissipation in smooth flow regions, and continuous turbulence inflow. In Duan et al (J. Fluid Mech. 2010), we analyzed the statistical data to characterize the effects of strong wall cooling. In Ringuette et al. (J. Fluid Mech. 2008), we developed a geometric algorithm that identifies hairpin heads, shear layers and hairpin packets associated with turbulent coherent structures on detailed three-dimensional data. The relationship between statistically (Brown & Thomas Phys. Flu. 1977) and geometrically (Ringuette et al.) identified structures can be described. In O’Farrel and Martín (2009), we were able to show that average ideal geometric events correspond to strong statistical ones. In Wu and Martin (JFM 2008), we studied the unsteady mechanism of shock and turbulent boundary layer interactions, and in Priebe & Martin (AIAA Paper 2011-725), we used spatially and temporally resolved data to describe the unsteady, aperiodic cycle, for the first time. In this talk, I will briefly discuss the type of experimental data useful in validating DNS data. I will present a sample problem where spatially and temporally resolved data was indispensable to understand the physical mechanisms at play. Then, using DNS data, statistical analyses and physics-based pattern identification algorithms, I will describe turbulent boundary layers over a wide parameter space, focusing on the influence of hypersonic conditions on the scaling of mean and turbulence behaviors, and the structure of turbulent boundary layers. Implications for the modeling and simulation of hypersonic turbulent boundary layers will be discussed. M. Pino Martín has been an Associate Professor of Aerospace Engineering in the University of Maryland since 2009. She is also affiliate faculty in the University of Maryland Institute for Computer Studies, which hosts her laboratory and about 100 Terabytes of detailed and validated numerical simulation data of turbulent flows. Her research interests include interdisciplinary approaches to the query and manipulation of turbulent flow using joined theoretical, numerical and experimental studies. She is the recipient of an NSF CAREER award in 2003 and the 2007 Alfred Rheinstein’11 Princeton University Faculty Award for “excellence in her chosen research field”. Prior to joining UMD, she was an assistant Professor in the Mechanical and Aerospace Engineering Department in Princeton University (2001-2009) and a Postdoctoral Research Fellow at the Center for Turbulence Research in Stanford University (2001) and the University of Minnesota (2000), after receiving a B.A. from Boston University (Summa cum laude 1994) and Ph.D. in Aerospace Engineering (1999) from the University of Minnesota under the guidance of Graham Candler.