Wed, Sep 14, 2022 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Werner Dahm, Arizona State University
Talk Title: Adaptive Scale-Similar Closure: Toward the Most General Stabilized Subgrid Model for Multi-Physics LES
Abstract: This seminar presents an adaptive scale-similar closure approach that can dynamically represent any subgrid term accurately and stably even at the smallest resolved scales of a simulation. The approach is based on scale similarity and generalized representations from the complete and minimal tensor representation theory of Smith (1971). At each point, the local tensor polynomial coefficients adapt to the local turbulence state via system identification at a test-filter scale and rescaling to the LES-scale. The methodology is demonstrated by applying it to the subgrid stress and subgrid scalar flux. Resulting fields for the subgrid terms and production rates are nearly indistinguishable from corresponding true fields, and are far more accurate than traditional subgrid models. Stability is ensured by a physics-based rational Boolean stabilization method, which uses the local subgrid production and subgrid redistribution rates to determine how individual subgrid components must be rescaled to provide local backward-transfer reduction or forward-transfer amplification. This produces only very small changes in the highly accurate fields for the subgrid terms and production rates that result from this new closure methodology. Together, adaptive scale-similar closure and rational Boolean stabilization essentially solve two key problems that have previously limited the accuracy of multi-physics large eddy simulations.
Biography: Werner J.A. Dahm is Professor Emeritus of Aerospace Engineering at the University of Michigan, where he was on the faculty for 25 years, and since 2010 has been the ASU Foundation Professor of mechanical and Aerospace Engineering at Arizona State University. Previously he served in the Pentagon as the Chief Scientist of the U.S. Air Force, and in numerous senior technical advisory roles, including on the Air Force Scientific Advisory Board since 2005 and as Chair of the Board from 2014-2017. He is an AIAA Fellow, an APS Fellow, and recipient of the Air Force Decoration for Exceptional Civilian Service and the Secretary of the Air Force Distinguished Public Service Award.
Host: AME Department
More Info: https://ame.usc.edu/seminars/
Location: Seaver Science Library (SSL) - 202
Audiences: Everyone Is Invited
Contact: Tessa Yao