SPH Numerical Simulations of the Deformation of a Liquid Surface in Two Dimensions

The Smoothed Particles Hydrodynamics (SPH) numerical method, DualSPHysics, was applied to simulate numerically the deformations generated when a solid object hits a liquid surface. In order to simplify the study, the simulations were carried out in 2D, with the hitting solid having a circular geometry. With the aim of comparing numerical and experimental results, a real quasi-2D cell was made using two acrylic walls with a 5 mm separation filled with water, using a slightly thinner Teflon disc as the hitting object. The simulation was able to reproduce qualitatively all the experimental phenomenology of the system, particularly the three main structures observed in the real quasi-2D (and also reported in 3D) situation: a crown splash, an air cavity, and a liquid jet. The maximum values reached by the depth of the cavity and the height of the jet were determined for two different impact velocities both numerically and experimentally. The numerical simulation better reproduced the experimental cavity depth than the jet height, with a percentage of average accuracy of 94% and 64% respectively. Accuracy was improved up to 85% for the maximum jet height when the effect of gravitational forces was increased and the maximum resolution was used in the numerical simulations. The differences found between experimental and simulation results can be attributed to the absence of a suitable model for surface tension in the single-phase system used to represent the free surface in the simulations, as well as to the confinement effects present in the experiments.