The operation of a 3D wave basin in force control

The present study concerns the generation and absorption of directional waves in a laboratory wave basin where both are based on force-feedback control. Many laboratories worldwide are now equipped with such technology, and the world's largest wave basin (the David Taylor Basin at the Naval Surface Warfare Centre, Carderock, USA) is currently being refurbished utilising force-driven wavemakers. Traditionally, the wave generation in such facilities was based on an empirical transfer function. In contrast, an entirely analytic approach is presented herein. A theoretical transfer function, enabling fully deterministic wave generation in a force-controlled three-dimensional wave basin, is derived for the first time. The theory is applicable to both flap- and piston-type wave machines. Even though the present study focuses on flap-type geometries, the results are readily adopted to the piston case. To demonstrate the successful application of the novel transfer function, a substantial experimental study is presented. As part of the experimental work, a direct comparison to an empirical transfer function is made and the benefits of either approach are discussed. Overall, very good agreement between the expected wave field and the experimental data is shown. However, some departures remain particularly for highly directional waves and broad-banded spectra.

► We review the operation of multi-directional wave basins.
► We derive a novel transfer function appropriate to absorbing force-controlled wave basins.
► We provide an experimental study confirming the validity of this transfer function.
► The theoretical transfer function partially removes the need for basin calibration.
► Some departures remain in the generation of very oblique waves at high frequencies.