Quantitative analysis on implicit large eddy simulation

Abstract

Current research conducts the quantitative comparisons between implicit large eddy simulation (iLES) and explicit eddy-viscosity large eddy simulation (eLES). iLES and eLES in a compressible Taylor–Green vortex problem are implemented with a fourth-order finite-volume gas kinetic scheme. Compared with the key statistical quantities of direct numerical simulation, iLES outweighs eLES on the exactly same unresolved grids. With DNS solution, a priori analysis of compressible filtered subgrid-scale (SGS) turbulent kinetic energy [Formula: see text] is performed. Forward and backward filtered SGS turbulent kinetic energy transfer coexists. The ensemble turbulent kinetic energy Ek is on the order of [Formula: see text] to [Formula: see text] of ensemble filtered SGS turbulent kinetic energy [Formula: see text]. The ensemble dominant physical dissipation rate [Formula: see text] is approximately 20 times larger than the ensemble filtered SGS dissipation rate [Formula: see text]. Then, for iLES and eLES, the total dissipation rate is decomposed into the resolved physical dissipation rate [Formula: see text], modeling SGS dissipation rate [Formula: see text], and numerical SGS dissipation rate [Formula: see text]. Quantitative comparisons on the modeling SGS dissipation rate and numerical SGS dissipation rate in iLES and eLES are evaluated. The numerical dissipation in iLES can be treated as the built-in SGS dissipation, which accounts for the reasonable performance of iLES. While the explicit modeling SGS dissipation in eLES pollutes the resolved turbulent structures in such low-Reynolds number turbulence. The next generation of large eddy simulation on unresolved grids must take into account both the built-in numerical SGS dissipation and its competition explicit modeling SGS dissipation.