Numerical simulation research about the drag reduction over riblet structure with different space of gyroidal object

The technology of the drag reduction over riblet surface is applied to underwater gyroidal object. The numerical simulation about riblet surfaces with different space has been carried out at various velocities. Some rules about riblet surface's drag reduction effect influenced by space are found out. Based on the characteristic of riblet surface's flow field of gyroidal object, computation model, region, grids and boundary condition are dealt with reasonably. The results of simulation show that at the same velocity pressure drag of riblet surfaces increases slightly and viscous drag, which is 80% of total drag, reduces remarkably compared with smooth surfaces, so it brings on drag reduction effect; drag reduction effect reaches the best while the space is three times of characteristic size of riblet structure; for the same riblet surface of gyroidal object, its drag reduction effect is more obvious at a low speed than a high speed.