Abstract
To investigate the synergistic drag-reducing effect of ribs and superhydrophobic surface, we perform direct numerical simulation (DNS) for a fully developed turbulent channel flow, in which the lower wall is superhydrophobic surface with ribs. In all computations presented here, a constant pressure gradient condition is employed, so that the positive drag reduction is evaluated as an increase of mass flux. For the case without ribs, the superhydrophobic property enhances the drag reducing effect, while for the case with ribs it reduces one.
