LARGE EDDY SIMULATION OF TURBULENT DRAG REDUCTION BY V-SHAPED RIBLETS

Turbulent flow over a riblet-covered surface is investigated numerically. The flow field has been simulated using Large Eddy Simulation (LES) technique. Comparison of computed turbulence statistics and mean velocity profile show good agreement with results obtained from Direct Numerical Simulation (DNS). Also, the computed drag on the riblet surfaces is in good agreement with the existing experimental data. It is concluded that Large Eddy Simulation with the proper grid resolution is capable to capture the complex features of the flow like secondary flows over riblets. Moreover, through numerical modeling, the distribution of cross-flow velocity and streamwise vorticity in near-wall fluid field are obtained, which are used to analyze the mechanism of the turbulent drag reduction over riblet surfaces.

Drag reduction, Riblet surface, Large eddy simulation, Turbulence structures