This paper presents a numerical investigation of vortex capture in a rectangular channel. We employ the Euler equations to describe the dynamics of an inviscid, incompressible fluid flowing through the channel, with defined normal velocity at both the inlet and outlet regulating the flow. Our findings show two key factors: the dissipation of vorticity and the reduction of vortex area influence vortex capturing. These factors interact in a feedback loop near the channel outlet. Vortex capture occurs when both processes halt. We also outline the numerical methods of analyzing planar vortex structures and provide relevant references.