Abstract: A hybrid finite difference and vortex method, which is based on domain decomposition and proposed by the authors (1992), is used forcalculating the flow around a rotating circular cylinder at Reynoldsnumber Re=1 000 and the rotation velocity ratio a∈(0.5,3.25) respectively. Some improvments are made in solution process: ahigh order full implicit difference algorithm is adopted, and the Solvers is replaced by a very efficient modified incomplete LU decomposition conjugate gradient method (MILU-CG). The long-...