Most sub-grid scale (SGS) models employed in LES (large eddy simulation) formulations were originally developed for incompressible, single phase, inert flows and assume transfer of energy based on the classical energy cascade mechanism. Although they have been extended to numerically study compressible and reactive flows involving deflagrations and detonations, their accuracy in such sensitive and challenging flows is an open question. Therefore, there is a need for both assessing these existing SGS models and identifying the opportunities for proposing new ones, which properly characterize reacting flows in complex engine configurations such as those characterizing rotating detonation engines (RDEs). Accordingly, accounting for the decay of free homogeneous isotropic turbulence (HIT), this work provides a comparison of four different SGS models when compressibility effects are present, (i) the classical Smagorinsky model, (ii) the dynamic Smagorinsky model, (iii) the wall-adapting local eddy-viscosity (WALE) model, and (iv) the Vreman model. More specifically, SGS models are firstly implemented in the open-source computational tool PeleC, which is a high-fidelity finite-volume solver for compressible flows, and then numerical simulations are carried out using them. The second-order explicit method of lines (MOL) and the hybrid PPM/WENO-Z method are utilized here as temporal and spatial numerical schemes, respectively. The numerical simulations are initialized at a turbulent Mach number of 0.6 and a Taylor Reynolds number of 100 , which are two nondimensional parameters defining the initial kinetic energy in the domain, after which the energy is transferred from large to small scales until it is eventually dissipated by viscous effects. In terms of results, turbulent spectra, and the decay of physical quantities such as kinetic energy, enstrophy, temperature, and dilatation are computed for each SGS LES model and compared with direct numerical simulations (DNS) results available in literature. The LES numerical results obtained here highlight that the studied SGS models are capable of capturing the overall trends of all physical quantities accounted for. However, they also emphasize the need of improved SGS models capable of adequately describing turbulence dynamics in compressible flows. The SGS model comparisons discussed in this work will serve as a basis for proposing in the future new SGS model constructs focused on compressible reactive flows.
Autor(es):CORDOVA, Jhon
CELIS, Cesar
MENDIBURU, Andres
BRAVO, Luis
KHARE, Prashant
Año: 2023
Título de la revista: 27th International Congress of Mechanical Engineering, COBEM2023 (ABCM)
Ciudad: Florianópolis, SC, Brazil
Url: https://doi.org/10.48550/arXiv.2309.05875