沿流向微结构沟槽流场直接数值模拟

To simulate the flow over the streamwise micro riblets of symmetric V shape, this paper applies a model of channel flow where the lower wall is mounted with riblets and the upper one is flat. The finite difference method is employed as the numerical method. To accurately obtain the flow of riblets, the 7th WENO (Weighted Essentially Non-Oscillatory) scheme, the fractional-step method combined with the Low-Dissipation and Dispersion Runge-Kutta scheme (LDDRK method) and the 6th central scheme are applied to the discretization of the space, the time advancing and viscous terms. In this paper, the Reynolds number is 5 000 (based on the half width of the channel), the range of the size of the riblets is from 13 to 44 and the inclination of the slope of riblets is 60°. Simulation results illustrate that the maximum of drag reduction is 9% and indicate that in the drag-reducing cases, the riblets can prevent the large-scale streamwise vortices from interacting with the surface directly, weakening the turbulent oscillation and decreasing the number of the streamwise vortices near riblet wall.