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In this paper, the ALE (Arbitrary Lagrangian-Eulerian) seamless immersed boundary method (ALE SIBM) with the overset grid for a rotating object is proposed and its effectiveness is discussed. In the ALE SIBM with the overset grid system, a main-grid and sub-grids are the Cartesian grids and the main-grid is generated throughout the computation domain and the sub-grids are generated only around each object. This sub-grid moves following the object by the ALE approach. Therefore, even if the object moves, the position of the object on the sub-grid does not change. In the past study, this method has been applied only to translating the object, not to rotating the object. In the present method, independent coordinate systems are set for the main-grid and the sub-grid in order to apply to rotational movement. As a result, coordinate transformation of the governing equations by rotation of the sub-grid following the object is unnecessary. In order to verify the effectiveness of the present method, flows around a 2-dimensional rotating circular cylinder and an elliptic cylinder ware considered. In the simulation of the flow around a 2-dimensional rotating circular cylinder, the results obtained by the present method ware in good agreement with the reference results. Therefore, it was shown that good results were obtained even when the sub-grid was rotated in the present method. In the simulation of the flow around a 2-dimensional rotating elliptic cylinder, it is expected that the results are improved by applying the present method because the position of the boundary of the elliptic cylinder changes on the single grid. From the above, it can be expected that flow simulations including an object with translation and rotation can be efficiently performed by applying the present method.

Computational Fluid Dynamics; Cartesian Grid Approach; Immersed Boundary Method; Incompressible Flow; Overset grid