This study presents a new hybrid algorithm for treating solid walls in the context of weakly–compressible SPH model. The basic concept is to fill an impervious region with some layers of dummy particles for improving the solution accuracy and a single layer of repulsive particles for imposing no-penetration condition along the solid–fluid interface. The latter consists of a new repulsion mechanism that, unlike the well known Lennard–Jones model, induces no pressure oscillation close to the wall. This hybrid boundary treatment technique is implemented in conjunction with a parameter–free SPH scheme to provide a Lagrangian solver for 2D Navier–Stokes equations. The accuracy of the model is verified by recourse to challenging numerical tests in free surface hydraulics, including dam break surging over dry bed with and without obstacle as well as free falling water jet from a sharp-crested weir. Comparison with relevant numerical and/or experimental data from the literature shows fair agreement in each case.
