Extrapolation Boundary Conditions for 2‐D Smoothed Particle Hydrodynamics

ABSTRACT This paper presents a new robust treatment for smoothed particle hydrodynamics (SPH) open (inflow/outflow) and solid boundary conditions, avoiding the unphysical fluctuations and numerical noise present in existing techniques. By novel use of concepts from finite volume methods, the fluid properties from sequential dynamic particles with different normal distances to the boundaries are extrapolated to ghost particles. No so‐called mirror points are required, making the method computationally efficient and easy to implement. The new methodology is validated through a series of progressively challenging test cases. The effectiveness of the wall and inflow‐outflow boundaries is evaluated for 2‐D Poiseuille laminar flow. The performance of the wall boundary for complex geometries is demonstrated using a hydrostatic tank with a triangular wedge, followed by a conventional 2‐D dam‐break problem to capture impact pressures. A range of challenging vertical inflows rarely explored using SPH, with varying efflux velocities, demonstrate highly accurate performance of the boundary treatment, with results compared to STAR‐CCM+. Finally, the robust performance is demonstrated for flow past circular and square cylinders over a range of Reynolds numbers, showing excellent results compared to reference results.