Projection algorithm for simulation of fluid flow around moving objects with immersed boundary method

Abstract

Abstract The simulations of fluid flow around moving objects are usually done using body conforming meshes, but recently there is growing interest in algorithms using non conforming grids, known as immersed boundary methods (IB). In particular the resolution of the flow around objects with moving boundary may involve a high meshing work that has to be repeated at each time step. In the present work the immersed boundary method is applied to an in-house finite element code, in order to simulate transient applications involving the movement of immersed solid interfaces. The distinguishing feature of this method is that the entire simulation is carried out on a grid which cover the entire domain and do not conform to the geometry of the rigid objects. A second mesh independent from the first one and built on the immersed body is considered. The presented method consists in the projection of fields, including boundary conditions, from the second mesh mentioned to the first one, that cover the whole domain. The projection is carried out considering the movement of the immersed objects, through the handling of the second mesh. The proposed algorithm is built in order to satisfy the mass conservation in the entire fluid region and to avoid any numerical instability. For the projection of such fields we develop a multiphysics open-source coupling platform, based on the open-source SALOME platform. MED (Modèle d’Échange de Donné) data structure has been used for all field operations, allowing the algorithm to be used with all the numerical codes where a MED duplicate of the field solution can be created. Applications of this approach will be presented and we provide results that show the consistency of the proposed algorithm.