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Large-Eddy Simulations of Wall Bounded Turbulent Flow

AMS Seminar Series

Speaker: Ravi Samtaney, The King Abdullah University of Science and Technology (KAUST)

Presentation

Seminar Slide Deck (PDF-14.2MB)

Abstract

We report recent progress on wall-modeled large-eddy simulation (LES) of wall bounded turbulent flows, including model development and case applications. The sub-grid-scale (SGS) model employed is the stretched spiral vortex SGS model, originally proposed by Misra & Pullin (Phys. Fluids 1997). The present wall-models is extensions of the original one proposed by Pullin & co-workers in a series of papers on LES of high Reynolds number flows in a channel, turbulent boundary layer, and a pipe. Our extensions to the wall model includes three parts: relaxation of the log-law assumption, extension into two-dimensional wall model and reformulation in generalized curvilinear coordinates.

Five flow configurations are examined in detail. The first case is that of a zero pressure gradient turbulent boundary layer in which our objective is to address whether the mean velocity profile obeys a log-law or a power-law. The second case is that of a separated and re-attached turbulent boundary layer, where the two-dimensional wall model is shown to reasonably predict the wall stress in the separated flow. The third case is flow over period hill, a benchmark case for LES modeling, and our LES show good results compared with experiments.

The fourth and perhaps more challenging case is that of a flow over a circular cylinder with emphasis on reproduction of the drag crisis at Re~O(10^5). One idea behind this is push the limit of LES on the supercomputer Shaheen II at KAUST. The final case is that of flows over airfoils, which is a prerequisite step for applying the present curvilinear wall model on cases with even more complex geometry. In all these, our emphasis is on validation and quantitative comparisons with experimental data when available.

Biography

Ravi Samtaney is presently a professor in Mechanical Engineering (Physical Science and Engineering Division) with a joint appointment in Applied Mathematics & Computational Science at the King Abdullah University of Science and Technology (KAUST) in the Kingdom of Saudi Arabia. He serves as Chair of the ME Program and Associate Dean of the PSE Division. Prior to KAUST, he was a Research Physicist at the Princeton Plasma Physics Laboratory, Princeton University, and a research faculty at the California Institute of Technology, and worked at NASA Ames Research Center. His research is at the intersection of applied mathematics, physics, and engineering, from fundamental processes in fluid mechanics (shocks, turbulence, ablation, ionization, etc.) to numerical methods and large-scale computing (adaptive meshing, scalable solvers, software engineering, etc.). He obtained his Ph.D. from Rutgers University in 1994.