File(s) under permanent embargo
Time-frequency analysis of ship wave patterns in shallow water: modelling and experiments
journal contributionposted on 2023-05-19, 18:42 authored by Pethiyagoda, R, Moroney, TJ, Gregor MacFarlaneGregor MacFarlane, Jonathan BinnsJonathan Binns, McCue, SW
A spectrogram of a ship wake is a heat map that visualises the time-dependent frequency spectrum of surface height measurements taken at a single point as the ship travels by. Spectrograms are easy to compute and, if properly interpreted, have the potential to provide crucial information about various properties of the ship in question. Here we use geometrical arguments and analysis of an idealised mathematical model to identify features of spectrograms, concentrating on the effects of a finite-depth channel. Our results depend heavily on whether the flow regime is subcritical or supercritical. To support our theoretical predictions, we compare with data taken from experiments we conducted in a model test basin using a variety of realistic ship hulls. Finally, we note that vessels with a high aspect ratio appear to produce spectrogram data that contains periodic patterns. We can reproduce this behaviour in our mathematical model by using a so-called two-point wavemaker. These results highlight the role of wave interference effects in spectrograms of ship wakes.
Australian Research Council
Transport for NSW
Publication titleOcean Engineering
Department/SchoolAustralian Maritime College
PublisherPergamon-Elsevier Science Ltd
Place of publicationThe Boulevard, Langford Lane, Kidlington, Oxford, England, Ox5 1Gb
Rights statementCopyright 2018 Elsevier Ltd. All rights reserved.