Mixed modeling for large-eddy simulation: The single-layer and two-layer minimum-dissipation-Bardina models

Abstract

Predicting the behavior of turbulent flows using large-eddy simulation requires a modeling of the subgrid-scale stress tensor. This tensor can be approximated using mixed models, which combine the dissipative nature of functional models with the capability of structural models to approximate out-of-equilibrium effects. We propose a mathematical basis to mix (functional) eddy-viscosity models with the (structural) Bardina model. By taking an anisotropic minimum-dissipation (AMD) model for the eddy viscosity, we obtain the (single-layer) AMD–Bardina model. In order to also obtain a physics-conforming model for wall-bounded flows, we further develop this mixed model into a two-layer approach: the near-wall region is parameterized with the AMD–Bardina model, whereas the outer region is computed with the Bardina model. The single-layer and two-layer AMD–Bardina models are tested in turbulent channel flows at various Reynolds numbers, and improved predictions are obtained when the mixed models are applied in comparison to the computations with the AMD and Bardina models alone. The results obtained with the two-layer AMD–Bardina model are particularly remarkable: both first- and second-order statistics are extremely well predicted and even the inflection of the mean velocity in the channel center is captured. Hence, a very promising model is obtained for large-eddy simulations of wall-bounded turbulent flows at moderate and high Reynolds numbers.

Investigation of thermal large-eddy simulation approaches in a highly turbulent channel flow submitted to strong asymmetric heating

“…The ILES solution combining the selected mesh and numerical scheme (mass convection and momentum convection are respectively approached with a Quick scheme and a fourthorder centered scheme) is compared to a no-model simulation. This no-model simulation aims to reproduce the one performed by Streher et al 48 in an isothermal turbulent channel flow at a friction Reynolds number of 950, see Fig. 3.…”

“…For mass convection, a Quick and a centered second-order schemes are compared. This last scheme has been used by Streher et al 48 in a LES study dealing with isothermal channel flow and produces very good results. High-resolution spatial discretization methods such as the compact finite difference schemes proposed by Lele 49 are not tested in this study.…”

Direct simulations and subgrid modeling of turbulent channel flows asymmetrically heated from both walls

“…We address first-order and second-order statistics. Functional and mixed models are respectively traceless and partially traceless meaning that only the deviatoric Reynolds stresses can be reconstructed and compared with DNS data without filtering process 44,68 :…”

“…Since the scheme is based on a quadratic function it is third-order accurate in terms of Taylor series truncation error. The second-order centered scheme, employed by Streher et al 44 , is also considered. The simulations are performed with TrioCFD software 67 .…”

“…37,[39][40][41][42][43] . Streher et al 44 propose a two-layer mixed model for the LES of isothermal channel flow: the near-wall region is parameterized with the combination of the AMD and the scale similarity model 45 , whereas the outer region is computed with the scale similarity model only. The obtained results are in very good agreement with the DNS of Moser et al 12 and Hoyas and Jiménez 15 .…”