Incompressible separated flows simulations with the smoothed particle hydrodynamics gridless method

The gridless Lagrangian method smoothed particle hydrodynamics (SPH) is preferentially used in CFD to simulate complex flows with one or several convoluted free surfaces. Indeed, this type of flow would require distorted meshes with Lagrangian finite difference methods or very fine meshes with VOF. As the literature is quite scarce concerning SPH validations for academic problems, we present in this paper some results relative to laminar recirculating flows. The ability of SPH to reproduce recirculation zone is revealed through a 2D hill and a backward-facing step geometry: axial velocity profiles obtained with SPH are quite satisfactory and separation and reattachment points are well predicted in both cases. Moreover, some practical and robust wall modelling conditions are also introduced and the limitation of the nearly incompressible assumption, used in most standard SPH codes, is illustrated. Indeed, we reveal that it is necessary to consider a relatively high speed of sound in order to avoid numerical voids. Copyright (c) 2005 John Wiley & Sons, Ltd.