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It’s getting more important to compute flow field around complex geometries such as energy saving devices (ESDs) for vessels in order to evaluate ship performance more rapidly and precisely. Overset grid approach is one of ways to deal with complex geometries, simplifying grid generation and it provides flexibility to rearrange geometries. Overset grid approach is also useful for a moving body problem since it can cope with change of arrangement of computational grids by just recomputing Domain Connectivity Information(DCI) without regenerating grids. UP_GRID and NAGISA are developed as an overset grid assembling system and a flow solver for overlapped grids based on URANS equation, respectively, at MPAT (National Institute of Maritime, Port and Aviation Technology, Japan). Flow simulation around Japan Bulk Carrier(JBC) with a rotating propeller are carried with dynamic overset approach by coupling the two codes. DCI is recomputed at each time steps by UP_GRID and flow field is updated by NAGISA using renewed DCI. Full multigrid method is used in order to get a fast convergence in NAGISA. It is confirmed that the system has capability to simulate unsteady flow field behind a ship with a rotating propeller by dynamic overset assembling approach practically.

Overset Assembling, Dynamic Overset, Unsteady Flow, Propeller, Full Multi Grid