Characteristics on drag reduction of bionic jet surface based on earthworm's back orifice jet

In order to reduce the drag reduction of the fluid on the solid wall, based on the biology characteristics of earthworm, the earthworm's back orifice jet characteristic is analyzed. The bionic jet surface is modeled by imitating the earthworm's back orifice jet, and the SST k-ω turbulent model is used for numerically simulating the drag reduction characteristics of bionic jet surface, simultaneously the result of the numerical simulation is verified experimentally. On this account, the drag reduction mechanism of bionic jet surface is studied based on the imitation of the earthworm's back orifice jet. The results show that under certain conditions, the drag reduction characteristics of bionic jet surface for imitating the earthworm's back orifice jet are very effective. At the same angle of jet direction, the drag reduction rate increases with the increase of jet velocity; at the same jet speed, the drag reduction rate presents a tendency to increase after the first decrease with increasing the angle of the jet direction. The maximum drag reduction rates obtained from numerical simulation and experimental measurement both on condition that jet velocity is 1 m·s-1 and the angle of jet direction angel is -30°, are 8.69% and 7.86%, respectively. Jet surface changes the original boundary layer structure in smooth wall, thereby effectively controlling the wall boundary layer, and reducing the wall shear stress and also the velocity of the wall boundary layer.