Autonomic Closure for Large Eddy Simulations


Motivated by the application of adjoint techniques for rapidly solving large optimization problems, a fundamentally new autonomic closure is discussed that allows an essentially model-free, dynamic subgrid-scale closure for large eddy simulations (LES). The autonomic closure addresses nonlinear, nonlocal, and nonequilibrium turbulence effects and, in its most general form, is based on all possible tensorally-invariant, dimensionally-consistent relations between the local subgrid-stress tensor and resolved scale primitive variables. This introduces a large matrix of spatially and temporally varying coefficients that can be optimized using a test filter approach and then applied at the LES filter scale by invoking scale similarity. The autonomic closure is intended to avoid the need to specify a model for the subgrid stresses, and instead allows the simulation itself to determine the best local relation between the subgrid stresses and resolved state variables. A priori tests of this approach are presented using data from direct numerical simulations of homogeneous isotropic turbulence, and application of the closure to practical simulations is discussed.

Sep 16, 2014 3:30 PM — 4:30 PM
Bechtel Collaboratory, Discovery Learning Center
Engineering Center, University of Colorado at Boulder, Boulder, CO 80309

National Renewable Energy Laboratory