Abstract
Upon entering shallow waters, ships experience a number of changes due to the hydrodynamic interaction between the hull and the seabed. Some of these changes are expressed in a pronounced increase in sinkage, trim and resistance. In this paper, a numerical study is performed on the Duisburg Test Case (DTC) container ship using Computational Fluid Dynamics (CFD), the Slender-Body theory and various empirical methods. A parametric comparison of the behaviour and performance estimation techniques in shallow waters for varying channel cross-sections and ship speeds is performed. The main objective of this research is to quantify the effect a step in the channel topography on ship sinkage, trim and resistance. Significant differences are shown in the computed parameters for the DTC advancing through dredged channels and conventional shallow water topographies. The different techniques employed show good agreement, especially in the low speed range.
Highlights
Ship behaviour and performance are highly influenced by the hydrodynamic interaction between the hull and the proximity of the seabed
A joint financed project with PIANC led to the creation of working group 4 (WG 4), which was tasked with providing recommendations for the optimal layout and dimensions of large ships in shallow waterways
In order to obtain a full picture of the ship behaviour in shallow water, the trim the vessel experiences, considered an indispensable part in the overall ship assessment, is given for each case-study
Summary
Ship behaviour and performance are highly influenced by the hydrodynamic interaction between the hull and the proximity of the seabed. The flow velocity between the hull’s bottom and the seabed increases, which produces a drop in pressure. The three main parameters influencing ship squat are the blockage factor (S), the block coefficient (CB), and the ship’s velocity (V ). The blockage factor can be defined as the ratio of the submerged midship cross-sectional area and the underwater area of the canal or channel (Fig. 1). This dimensionless parameter is utilised in calculating ship squat by empirical formulations, and is shown in Eq (1): bT. The CFD numerical technique used is put into historical perspective
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Published Version
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