Session: 06-16-01 Wave Mechanics, Modeling and Wave Effects

Submission Number: 156443

Hybrid Physical-Numerical Modelling of Following Wave-Current Interaction 

This study compares the effect of a following current on the evolution of regular waves in a physical and numerical wave-current flume. A following current stretches the waves, increasing their wavelength and decreasing their amplitude. Conventional wavemaker theories do not account for currents, making it challenging to calibrate the wavemaker motion to achieve desired wave conditions at specific locations. This typically requires multiple iterations, reducing the number of test conditions within a given timeframe. Adopting a hybrid physical – numerical modelling approach within an experimental facility can potentially reduce the amount of iterations required to calibrate the wavemaker motion. Furthermore, numerical simulations give the solution over the entire domain, whereas the number of physical measurement instruments is limited and possibly interfering with the flow. When selecting a numerical model to serve as numerical equivalent for a physical facility, a trade-off has to be made between numerical efficiency and accuracy. In this study, we opted for the High-Order Spectral – Numerical Wave Tank (HOS-NWT), an efficient nonlinear free surface potential flow solver dedicated to simulating waves in a wave basin. The code has been modified to account for the presence of a uniform current in the dynamic and kinematic free surface boundary conditions. The results of this modified version of HOS-NWT are compared to physical measurements with both waves and currents in the Coastal & Ocean Basin (COB) in the Flanders Maritime Laboratory in Ostend, Belgium. During these experiments, a confined section of 3 m wide was demarcated within the basin. The current enters the COB from a flow-chamber underneath the basins floor and interacts with the waves over a section with a length of ca. 14 m, before returning to the flow-chamber. To mimic this in the numerical model, the current velocity is gradually increased/decreased on top of the flow inlet/outlet using an Hermite polynomial. The wave conditions in the middle of the current section are compared between the numerical and physical model. This is done for seven different regular waves at three different current velocities, as well for the waves without a current.

Presenting Author: Tim Aertsens KU Leuven & The University of Melbourne

Presenting Author Biography: Tim Aertsens did both his Bachelor’s in Engineering Science and his Master’s in Civil Engineering at the KU Leuven in Belgium. During his Master’s, he did an exchange of one semester to Polytechnique Montreal. After his graduation, he was granted a Strategic Basic Research Fellowship by The Research Foundation – Flanders (FWO) for his joint PhD project at KU Leuven and The University of Melbourne. His research focuses on optimizing the combination of numerical and physical modeling to study multidirectional wave-wave, wave-current, and wave-structure interactions.