Abstract: A numerical method is presented here to solve the internal and eXternal flow near/ between ring wing and hulls of submerged weapons.The internal and external flow of full domain can be solved together by adopting semi-staggered grid system in which the boundary conditions of foils of the ring wing and hull are convenient to implement.The calculation of pressure is based on a continuity equation formulation which is similar to the artificial compressible method.The internal and external flow are calculated w...