Smooth particle hydrodynamics (SPH) is a Lagrangian particle method for modeling impacts, explosions or fluid–structure interaction (FSI) problems.
The method was developed to avoid the limitations of mesh entangling encountered with the finite element method in extreme deformation problems, and to model complex free surface and material interface behaviors, including solid fragmentation. A main difference between classical methods and SPH is the absence of a grid: The particles are the computational framework on which the governing equations are resolved.
SPH has been applied extensively to problems involving incompressible flows, heat conduction, high explosives and high velocity impacts. The SPH method in Ansys LS-DYNA® is coupled with the finite and discrete element methods, extending its range of applications to a variety of complex problems involving multiphysics.