Numerical simulation on hysteresis phenomenon of side-jets formation in a round jet

Abstract

A jet may be ejected not only in the mainstream direction but also in the outward direction near the nozzle exit. This bifurcating phenomenon is called side jet. In recent experiments, it is confirmed that when the jet velocity is increased or decreased, a hysteresis phenomenon occurs in the formation of side jets. It is expected that the phenomenon is related to the acceleration of jet velocity. Therefore, we have attempted to investigate the effect of acceleration and deceleration on the formation of side jets using numerical simulation. As a result, it is found that by slowing down the issuing velocity of a jet, the side jets disappear as they move downstream. In this process, side jets occur even in the Reynolds number that is not seen at the time of acceleration.