SPH modeling of dissipation mechanisms in gravity waves Andrea Colagrossi ∗ CNR-INSEAN, The Italian Ship Model Basin Via di Vallerano 139, 00128 ROMA, Italy CESOS/CAMOS: Centre for Excellence for Ship and Ocean Structures, NTNU, Trondheim, Norway Antonio Souto-Iglesias † Naval Architecture Department (ETSIN), Technical University of Madrid (UPM), 28040 Madrid, Spain Matteo Antuono ‡ and Salvatore Marrone § CNR-INSEAN, The Italian Ship Model Basin Via di Vallerano 139, 00128 ROMA, Italy (Dated: June 11, 2015) Abstract The Smoothed Particle Hydrodynamics (SPH) method has been used to study the evolution of free- surface Newtonian viscous flows specifically focusing on dissipation mechanisms in gravity waves. The numerical results have been compared with an analytical solution of the linearized Navier-Stokes equations for Reynolds numbers in the range 50 − 5000. We found that a correct choice of the number of neighboring particles is of fundamental importance in order to obtain convergence towards the analytical solution. This number has to increase with higher Reynolds numbers in order to prevent the onset of spurious vorticity inside the bulk of the fluid, leading to an unphysical over-damping of the wave amplitude. This generation of spurious vorticity strongly depends on the specific kernel function used in the SPH model. PACS numbers: 47.11.-j, 47.15.-x, 47.10.ad Keywords: Smoothed Particle Hydrodynamics, numerical stability, gravity waves, viscous dissipation, spurious vorticity ∗ Electronic address: andrea.colagrossi@cnr.it † Electronic address: antonio.souto@upm.es 1