Wall y+ approach for dealing with turbulent flows over a surface mounted cube: part 2 - high Reynolds number

Abstract

An approach for dealing with turbulent flows over a surface-mounted cube using the wall y + as guidance in selecting the appropriate grid configuration and corresponding turbulence models are investigated using Fluent. The study is divided into two parts- Part I and Part II, dealing with low and high Reynolds number, respectively. Part I dealt with a low Reynolds number of 1,870. In Part II presented here, a Reynolds number of 40,000 based on cube height and bulk velocity is investigated and the computational results are compared with experimental data from Martinuzzi et al. (1993) on „the flow around surface-mounted, prismatic obstacles placed in a fully developed channel flow‟. The standard ke, standard k-ω, Reynolds Stress Model (RSM), SpalartAllmaras (SA) and renormalization group (RNG) k-e models are used to solve the closure problem. Their behaviour together with the accompanying near-wall treatments is investigated for wall y + ≈5 covering the viscous sublayer, y + ≈22 the buffer region and y + ≈33 resolving the log-law region, unlike the previous study (Part I – Ariff et al., 2009) which could only resolve the viscous sublayer and buffer region due to the comparatively lower Reynolds number. It is concluded that the mesh resolving the log-law region is sufficiently accurate without incurring additional computational cost. RSM turbulence model best predicts the flow separation region above the cube whereas the standard k-e performs better in the flow reattachment and recovery regions.