Study of mesh sensitivity and temporal discretization influence on the generation of realistic irregular waves through the WaveMIMO methodology

The present study addresses the investigation of mesh sensitivity in the free surface (FS) region and the discretization of the time step (Δt) used in the generation of irregular waves through the WaveMIMO methodology. In this study, this methodology treats data that comes from the TOMAWAC spectral model to obtain realistic orbital velocity profiles of wave propagation, which are subsequently imposed as inlet boundary conditions in the wave channel. Therefore, realistic data are considered relating to a point close to Molhes da Barra in Rio Grande, Rio Grande do Sul. The numerical simulations were carried out in Fluent, a computational fluid dynamics software based on the finite volume method. The volume of fluid multiphase model was used to treat the water-air interface. For the discretization of the FS, four cases were investigated, the first was suggested in the literature, and the other three cases subdivided the region into 4 segments, which presented different discretizations among them. Regarding temporal discretization, 4 different cases were compared, relating the time step to the mean period (Tm) of the sea state considered. The best results were obtained for the combination of 60 mesh elements in FS and Δt = Tm/120.