New Insights into Large Eddy Simulation

Fluid dynamic turbulence is one of the most challenging computational physics problems because of the extremely wide range of time and space scales involved, the strong nonlinearity of the government equations, and the many practical and important applications. While most linear fluid instabilities are well understood, the nonlinear interactions among them makes even the relatively simple limit of homogeneous isotropic turbulence difficult to treat physically, mathematically, and computationally. Turbulence is modeled computationally by a two stage bootstrap process. The first stage, Direct Numerical Simulations, attempts to resolve the relevant physical time and space scales but its application is limited to diffusive flows with a relatively small Reynolds number Re. Using Direct Numerical Simulation to provide a database, in turn, allows calibration of phenomenological turbulence models for engineering applications. Large Eddy Simulation incorporates a form of turbulence modeling applicable when the large-scale flows of interest are intrinsically time dependent, thus throwing common statistical models into question. A promising approach to large Eddy Simulation involves the use of high-resolution monotone computational fluid dynamics algorithms such as Flux-Corrected Transport or the Piecewise Parabolic Method which have intrinsic subgrid turbulence models coupled naturally to the resolves scales in the computed flow. The physical considerations underlying and evidence supporting this Monotone Integrated Large Eddy Simulation approach are discussed. Flux-corrected transport Large-eddy simulation Shear flows Subgrid modeling Turbulence