Using a Half-Implicit Integration Scheme for the SPH-based Solution of Fluid–solid Interaction Problems

A Smoothed Particles Hydrodynamics (SPH) method for fluid dynamics is coupled with a rigid and deformable body dynamics solution to yield a framework for solving fluid–solid interaction (FSI) problems. The two-way, force–displacement, coupling of the fluid and solid phases is captured via boundary condition enforcing (BCE) markers. The partial differential equations governing each phase are discretized in space separately and the resulting ordinary and/or algebraic differential equations are integrated in time independently with coupling enforced via fluid–solid boundary conditions. Particular attention is paid to enforcing fluid incompressibility via a projection step that computes the pressure field as the solution of a linear system. The numerical solution leverages hybrid parallel computing: the rigid and flexible body dynamics is handled on the CPU using multiple cores; at the same time, the fluid phase is handled on the graphics processing unit (GPU). The methodology is validated against experimental data and numerical results obtained using two open-source solvers. Several case studies are reported to gauge the accuracy, efficiency, and scalability of the solver. The highlights of the proposed solution are: tight enforcement of fluid incompressibility; ability to handle coupled physics that combines fluid, rigid, and deformable bodies; ability to handle friction and contact; and, scalable implementation that simultaneously employs CPU and GPU computing.