Title: Convergence study of the Chorin-Marsden formula Speaker: Professor Longan Ying, Peking University and Penn State University Date and place: Friday Apr. 14 3:30pm at UNIV 101 abstract. The vortex method is applied to simulating viscous flow numerically. The advantage of the vorticity-stream function formulation is that it provides the motion of vorteces directly and it is one approach for high-Reynold's number flow. The difficulty of the vorticity-stream function formulation is that there is no a local vorticity boundary condition. A "vorticity creation operator" is introduced in the Chorin-Marsden formula to replace the boundary condition. In this talk, We will present our study on the convergence problem of the Chorin-Marsden formula for bounded domains. We first consider the exact solution and introduce an integral equation with Volterra type for the density of the vortex sheet, then we prove the convergence of the approximate solutions. The order of convergence is estimated, which is belived to be optimal. An comparison is made for different kinds of approximate vortex sheets.