Usability of explicit filtering in large eddy simulation with a low‐order numerical scheme and different subgrid‐scale models

Abstract

SUMMARYBased on a priori tests, in large eddy simulation (LES) of turbulent fluid flow, the numerical error related to low-order finite-difference-type methods can be large in comparison with the effect of subgrid-scale (SGS) model. Explicit filtering has been suggested to reduce the error, and it has shown promising results in a priori studies and in some simulations with fourth-order method. In this paper, the effect of explicit filtering on the total simulation error is studied together with a second-order scheme, where the numerical error should be even larger. The fully developed turbulent channel flow between two parallel walls is used as a test case. Rather simple SGS models are applied, because these models are most likely used in practical applications of LES. Explicit filtering is here applied to the non-linear convection term of the Navier-Stokes equations, four three-dimensional filter functions are applied, and the effect of filtering is separated from the effect of SGS modelling. It is shown that the effect of filtering is rather large and smooth filters introduce an additional error component that increases the total simulation error. Finally, filtering via subfilter-scale modelling is applied, and it is shown that this approach performs better. However, the large-frequency components of the resolved flow field are not as effectively damped as when the non-linear convection term is filtered.

Implicit Large Eddy Simulation of weakly-compressible turbulent channel flow

“…There are several research studies concerning classical LES of turbulent channel flow. Previous studies [47][48][49][50] (and references therein) have dealt with the development of SGS models; error contributions from SGS modelling and numerical schemes [19,[51][52][53][54]; error control through explicit filtering [53,55,56]; and the effects of different filtering procedures [20,57,58].…”

“…The effect of the different filtering methods was also examined in a subsequent study [57] showing that three-dimensional filtering gives better results than two-dimensional filtering. In [58], it was reported that the effect of filtering can be significant, with smooth filters increasing the total simulation error. Recently, [20] investigated the use of explicit filtering in LES for obtaining grid independent numerical solutions similar to the work of [61].…”

Analysis of Unsteady Rotor–Stator Flow with Variable Viscosity Based on Experiments and CFD Simulations

“…The next stage of this study is to further simplify the passage model and adopt the hexahedral structured grid meshing method. We will choose Detached Eddy Simulation (DES) or Large Eddy Simulation (LES) turbulence model combined with a Volume of Fluid (VOF) two-phase flow model in order to accurately predict the distribution of gas-liquid two-phase flow within passages [16], and to capture more precisely the process of turbulent evolution. In addition, the method described here can be utilized to precisely calculate calorific value and is beneficial to the design of heat exchangers [17].…”

Computational aerodynamics: Advances and challenges

“…Classical LES studies have dealt with the development of SGS models and error contributions from SGS modelling (Stolz et al (46,47) , Hickel et al (48,49) and references therein) and numerical schemes (50)(51)(52)(53)(54) ; error control through explicit filtering (53,55,56) ; and the effects of different filtering procedures (57)(58)(59) . Recent developments of explicit SGS models include the approximate deconvolution model (ADM) (46) , which is an approximation of the nonfiltered field by means of a truncated series expansion of the inverse filter operator.…”

“…The effect of the different filtering methods was also examined in a subsequent study (58) showing that three-dimensional filtering gives better results than two-dimensional filtering. Brandt (59) reported that the effect of filtering can be significant, with smooth filters increasing the total simulation error. Recently, Bose et al (57) investigated the use of explicit filtering in LES for obtaining grid-independent numerical solutions similar to the work of Gullbrand (62) .…”