- Author
-
Meneveau, C.
- Title
- Physics and Modeling of Small-Scale Turbulence for Large Eddy Simulation. BFRL Fire Research Seminar. VHS Video.
- Coporate
- Johns Hopkins Univ., Laurel, MD
- Report
-
Video
May 26, 1998
- Keywords
-
turbulence
|
simulation
- Abstract
- The need to understand, predict and control tubulent flows poses a continued challenge from both fundamental and technological points of view. Large Eddy Simulation (LES) is emerging as the approach with the most promising chances of yielding practically useful results while being consistent with basic principles of turbulence phenomenology and theory. One of the most important issues for LES is subgrid-scale (SGS) modeling, the parameterization of the subgrid stresses in terms of the resolved, large scles of motion. Models must provide realistic rates of kinetic energy dissipation. It is thus of particular interest to examine experimental data to measure such rates in various flows and quantify how well particular models reproduce the observations. We examine an experimental surrogate of the subgrid (SGS) dissipation rate, by means of high-Reynolds number experimental data in the cylinder wake. Mean profiels are measured and compared (a-priori) with several models (Smagorinsky, similarity model, dynamic Smagorinsky). More detailed comparisons are achieved by means of conditional averaging, both with outer intermittency, and with the phase of coherent structures (Karman vortices) in the near wake. The results provide evidence that learning from resolved scales (such as in the dynamic and similarity models) leads to more realistic predictions than the constant coefficient eddy viscosity model, when turbulence is spatially complex and when coherent structures affect the SGS dynamics directly.