Numerical evaluation method of turbulence drag reduction with riblets

In order to apply numerical simulation method based on Reynolds-averaged Navier-Stokes (RANS) equations to drag reduction with riblets, inspired by the roughness model-Wilcox and after a deeper study on the effect of the value of ω near wall in k-ω shear stress transport (SST) turbulence model, it turns out that an increasing of wall ω in viscous sublayer leads to a decreasing of turbulent kinetic energy, turbulent viscosity and Reynolds shear stress, which shows the same change as realistic riblets. Based on the classical experimental data of riblets with symmetric V grooves (height=width), by introducing the effect factors pressure gradients and yaw angle, a modeling function between riblets geometry size and the value of wall ω is established in complex flow conditions. Comparing with the experimental data confirms that the modeling riblets can predict the drag reduction as realistic riblets. Besides, a detailed application method of modeling riblets is proposed. At last, an overall design and evaluation of the drag reduction by riblets is given in the case of the C919 wing-body combination.