Implementation of a new discrete Immersed Boundary Method in OpenFOAM

Abstract

International audienceThe immersed boundary method proposed by Pinelli et al. (2010) has been implemented as a new object oriented library within the open source CFD solver OpenFOAM for incompressible bluff body fluid flows. The method encompasses the presence of fixed and moving solid obstacles in a computational mesh, without conforming to their boundaries. Standard Cartesian meshes are employed(uniform or stretched), which allows to use efficient and accurate flow solvers. The immersed obstacles are defined using a body force added on the conservation equations, and evaluated on Lagrangian markers that can move over the Eulerian mesh to capture the motion or the deformation of the body. The integration of the method in the finite-volume formalism and the succesfull integration of the method into the PISO algorithm will be detailed and a careful verification will be provided using a manufactured solution. The efficiency and the accuracy of the algorithm has been studied on various 2D and 3D simulations of flows around fixed and moving cylinder , including careful comparisons with available numerical and experimental results of the literature. Analysis of the computational cost, numerical behavior and accuracy of the numerical method show that the global properties of the OpenFOAM solver are not alterated. A quasi-linear scalability with the number of processors (up to 96) is obtained, with a slope slightly lower than the ideal scalability a feature that has been reported already in existing OpenFOAM studies. Work has been validated at Reynolds numbers in the range Re=30-500 and is in good agreement with reference data reported in the literature. Work is already in progress to extend the algorithm to the simulation of fluid structure interaction with induced oscillation and turbulent flows around bluff bodies for which preliminary results are in good agreement with reference data reported in the literature