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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.

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The predictive capability of Detached Eddy Simulations (DES) is investigated in stationary as well as rotating ribbed ducts with relevance to the internal cooling of turbine blades. A number of calculations are presented at Re=20,000 and rotation numbers ranging from 0.18 to 0.67 with buoyancy parameters up to 0.29 in a ribbed duct with ribs normal to the main flow direction. The results show that DES by admitting a LES solution in critical regions transcends some of the limitations of the base RANS model on which it is based. This feature of DES is exemplified by its sensitivity to turbulence driven secondary flows at the rib side-wall junction, to the effect of Coriolis forces, and centrifugal buoyancy effects. It is shown that DES responds consistently to these non-canonical effects when RANS and URANS with the same model cannot, at a cost which is about a tenth of that of LES for the geometry and Reynolds number considered in this study.