%A QIN Suyang,XIANG Yang,LIU Hong %T Comparative Study of Kinematics Characteristics of Vortex Rings Generated by Piston and Disc %0 Journal Article %D 2016 %J Journal of Shanghai Jiao Tong University %R %P 294-299 %V 50 %N 02 %U {https://xuebao.sjtu.edu.cn/CN/abstract/article_40901.shtml} %8 2016-02-29 %X Abstract： Numerical methods were used to simulate the formation of vortex rings while the methods of stream function and Lagrangian coherent structures were applied to analyze the physical characteristics of vortex rings. It is found that the vortex rings generated by two mechanisms belong to thin core vortex. The distribution of vorticity in core is Gauss distribution which has a unified model. Due to the difference between formation environments, there are several differences between kinematics characteristics, mainly in transportation velocity and nondimensional core radius. Thus, the pure vortex rings generated by piston can reveal the mechanism of the flow over a body which is like disc and airfoil.