Numerical re-creation of multi-directional waves in a circular basin using a particle based method

Abstract

Numerical wave basins are a powerful tool for the study of fluid-structure interaction (FSI) problems in coastal and ocean engineering fields. Once well validated, numerical wave basins can offer significant advantages over experimental testing in terms of the number and type of available data-streams, and the associated cost. However, conventional numerical wave tanks tend to be limited to the generation of long-crested conditions, and struggle to properly model large fluid deformations along with wave-induced floating body motions and pressure distribution on structures. Here, for the first time we create, and validate, the short-crested wave fields in a circular wave basin, using a particle-based method to solve the full 3D Navier-Stokes equation. The model is based on the FloWave facility at the University of Edinburgh: the geometry enables the generation of multi-directional waves, and the particle-based-approach enables large fluid deformations to be automatically modelled. Multi-directional waves are generated with differing values of steepness and directional spreading, and simulated surface elevations are compared to experimentally-obtained data.Acceptable agreement is found between measured and modelled surface elevation values. Better performance is confirmed for lower-steepness wave cases; where r2 values of greater than 0.7 are found for all cases, and errors in significant wave height range between −8% and +1%. Greater under-production is found for higher-steepness conditions with a −10% to −16% error in significant wave height. It is concluded that a greater number of particles with smaller radius is required to accurately capture the smaller higher frequency disturbances. It is suggested, however, that as the lower-frequency components are well produced for all cases that the model is already suitable for the majority of FSI problems in both uni- and multi-directional wave fields.