Detached Eddy Simulation of Turbulent Flow and Heat Transfer in a Ribbed Duct

Detached Eddy Simulation (DES) of a hydrodynamic and thermally developed turbulent flow is presented for a stationary duct with square ribs aligned normal to the main flow direction. The rib height to channel hydraulic diameter $(e∕Dh)$ is 0.1, the rib pitch to rib height $(P∕e)$ is 10 and the calculations have been carried out for a bulk Reynolds number of 20,000. DES calculations are carried out on a $963$ grid, a $643$ grid, and a $483$ grid to study the effect of grid resolution. Based on the agreement with earlier LES computations, the $643$ grid is observed to be suitable for the DES computation. DES and RANS calculations carried out on the $643$ grid are compared to LES calculations on $963∕1283$ grids and experimental measurements. The flow and heat transfer characteristics for the DES cases compare well with the LES results and the experiments. The average friction and the augmentation ratios are consistent with experimental results, predicting values within 10% of the measured quantities, at a cost lower than the LES calculations. RANS fails to capture some key features of the flow.