抄録
Generally, a vortex ring can be generated by piston motion in a cylindrical tube. Some past studies had presented a condition to generate equivalent vortex rings from orifice outlet to those from straight nozzle outlet, whose diameter equal to piston diameter. In this paper, we numerically simulated the vortex rings generated by both the straight outlet and orifice outlet. However, it found that the condition cannot generate the equivalent vortex rings and we need to modify the condition.
