Comparison of zonal RANS and LES for a non-isothermal ribbed channel flow

Abstract

Numerical simulations for a non-isothermal ribbed channel flow are made. Due to the relatively low Reynolds number ( Re = 14,200, based on the channel height), the results have relevance to higher Reynolds number electronics cooling systems. Through considering a k– l based zonal large Eddy simulation (ZLES) method and the S–A based detached Eddy simulation (DES) approach, the predictive accuracy of hybrid methods is assessed. This is assisted through comparisons with Reynolds-averaged Navier–Stokes (RANS) model results and also measurements. The RANS models used are the zonal k– l/EASM (explicit algebraic stress model) and k– l/cubic (non-linear cubic). The k– l modelling in these is just used near walls. Comparison reveals that both ZLES and DES are capable of capturing complex unsteady flow features associated with flow separation and reattachment. In general, for the present case, ZLES and DES perform similarly and are in better agreement with measurements than results from the zonal RANS. ZLES and DES heat transfer predictions are encouraging, the model sensitivity of results displayed when using RANS approaches being much less marked.