Verification and validation of a numerical wave tank with momentum source wave generation

Abstract

A systematic verification and validation (V&V) of our previously proposed momentum source wave generation method is performed. Some settings of previous numerical wave tanks (NWTs) of regular and irregular waves have been optimized. The H2-5 V&V method involving five mesh sizes with mesh refinement ratio being 1.225 is used to verify the NWT of regular waves, in which the wave height and mass conservation are mainly considered based on a Lv3 (H_s = 0.75 m) and a Lv6 (H_s = 5 m) regular wave. Additionally, eight different sea states are chosen to validate the wave height, mass conservation and wave frequency of regular waves. Regarding the NWT of irregular waves, five different sea states with significant wave heights ranging from 0.09 m to 12.5 m are selected to validate the statistical characteristics of irregular waves, including the profile of the wave spectrum, peak frequency and significant wave height. Results show that the verification errors for Lv3 and Lv6 regular wave on the most refined grid are −0.018 and −0.35 for wave height, respectively, and −0.14 and for −0.17 mass conservation, respectively. The uncertainty estimation analysis shows that the numerical error could be partially balanced out by the modelling error to achieve a smaller validation error by adjusting the mesh size elaborately. And the validation errors of the wave height, mass conservation and dominant frequency of regular waves under different sea states are no more than 7%, 8% and 2%, respectively. For a Lv3 (H_s = 0.75 m) and a Lv6 (H_s = 5 m) regular wave, simulations are validated on the wave height in wave development section for safety factors FS ≈ 1 and FS ≈ 0.5–1, respectively. Regarding irregular waves, the validation errors of the significant wave height and peak frequency are both lower than 2%.