Low-order isotropic spatial resolution characteristics of the viscous terms for LES analysis on iso/anisotropic steady turbulent flows

Abstract

Abstract This study aims to clarify the effect of reducing the isotropic spatial resolution on the turbulence field obtained in the Large Eddy Simulation (LES). Here, isotropic or anisotropic steady turbulence is analysed in this LES. A linear forcing method is used to generate these steady turbulent flows. Although the spatial resolution can be enhanced by increasing the number of spatial grid points or by using higher-order discrete forms, the isotropic resolution is only sometimes maintained. This viewpoint is expected to be particularly evident in the present study, especially in the LES analysis of wall turbulence. The present study focuses mainly on the spatial resolution of the viscous terms, where the spatial resolution can be varied while maintaining isotropy. Here, the discretisation accuracy order of the viscous terms was set from second to eighth order. In this study, the discretisation accuracy order of the convection terms is also varied. As shown in this study, the effect of the viscous term on the turbulence fields is larger than that of the discretisation accuracy order of the convection terms. There is a difference in the characteristics of the turbulence field obtained when the discretisation accuracy of the viscosity terms is of second and fourth or higher order.