Modelling the hydrodynamic effect of abrupt water depth changes on a ship travelling in restricted waters using CFD

ABSTRACT

Shallow water studies of ship hydrodynamics typically examine a single, constant underwater canal cross-section at a time. In practice, the underwater cross-sectional area and shape of the waterway is rarely maintained constant over long distances. This study presents an attempt to quantify the effects of an abruptly varying water depth by numerically modelling such a condition using CFD. The results show that waves propagate and refract in the numerical towing tank in a physically consistent manner showing less than 0.1% error in the dissipation of a solitary wave when compared to analytical relations. A strong boundary layer is formed on the canal bottom almost as soon as the ship enters the shallower region. The resistance increase, resulting from the depth change is up to approximately 226% of the initial value near critical speeds.

KEYWORDS:

• Shallow water
• restricted water
• RANS
• wavefield
• step change in water depth
• water depth transition

Acknowledgements

Results were obtained using the ARCHIE-WeSt High Performance Computer (www.archie-west.ac.uk) based at the University of Strathclyde. The work reported in this paper is drawn from the first author’s PhD thesis. The first author gratefully acknowledges the scholarship provided by the Faculty of Engineering at the University of Strathclyde, which fully supports his PhD.

Disclosure statement

No potential conflict of interest was reported by the author(s).