Quantitative analysis on implicit large eddy simulation.

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 ρ ¯ K sgs f is performed. Forward and backward filtered SGS turbulent kinetic energy transfer coexists. The ensemble turbulent kinetic energy Ek is on the order of o (10 4) to o (10 2) of ensemble filtered SGS turbulent kinetic energy K sgs f . The ensemble dominant physical dissipation rate ε 1 is approximately 20 times larger than the ensemble filtered SGS dissipation rate − τ i j f S ̃ i j f . Then, for iLES and eLES, the total dissipation rate is decomposed into the resolved physical dissipation rate ε phy , modeling SGS dissipation rate ε sgs mod , and numerical SGS dissipation rate ε sgs num . 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. [ABSTRACT FROM AUTHOR]