Study on Large Eddy Simulation and Drag Reduction Mechanism of Triangular Riblets

Experiments have shown that the triangular riblets have a good effect on surface drag reduction, but it is difficult to simulate and reveal the mechanism of riblets drag reduction by Reynolds averaged turbulence model. In this paper, large eddy simulation (LES) was used to simulate the channel flow with riblets which installed on the lower wall. The accuracy of the calculation in this paper was confirmed by the comparison between the calculated drag reduction rate and the experimental value, as well as the comparison of the mean velocity profile and the RMS velocity with the direct numerical simulation (DNS) results. According to the detailed analysis of the calculated flow field, it is shown that the shear force near the riblets wall is smaller than that of the plate, and the drag reduction is achieved by increasing the thickness of the boundary layer in the near-wall area, inhibiting the development of the stream wise vortex and reducing the near-wall activity.