LES analysis clarifying the response of static pressure fluctuation characteristics in isotropic/anisotropic steady turbulence field to reducing isotropic small-scale spatial resolution

Abstract

This study aims to clarify the effects of an isotropic reduction in spatial resolution on the characteristics of the static pressure fluctuation in isotropic/anisotropic statistically steady state turbulence. Although previous direct numerical analyses have investigated the static pressure fluctuation, this study considers it as a quantity that could be more straightforwardly obtained from experimental measurements and numerical analyses. To address this issue, a large-eddy simulation is used in this study. The Smagorinsky model, the Vreman model and the implicit LES model are used in this study to model sub-grid scale fluctuations. The influence of isotropic spatial resolution reduction is set by changing the accuracy order for the discretisation of the viscous terms from second to eighth order, based on a three-dimensional cubic computational domain with spatially uniform computational grid width. The accuracy order for the convection terms is also set to second and fourth order in this study. When the discretisation accuracy order of the viscous terms is second order, there is a significant reduction in the accuracy of the implicit LES. The discretisation accuracy order of the viscous terms should be set to fourth order or higher, as seen in this study. In addition, unlike the turbulent kinetic energy, different discretisation accuracy orders for the viscous and convective terms also have a non-negligible effect on the static pressure fluctuation analysis.