Full-scale unsteady RANS CFD simulations of ship behaviour and performance in head seas due to slow steaming

Full-scale unsteady RANS simulations of vertical ship motions in shallow water

Investigation of self-propulsion of DARPA Suboff by RANS method

As a ship approaches shallow water, a number of changes arise owing to the hydrodynamic interaction between the bottom of the ship’s hull and the seafloor. The flow velocity between the bottom of the hull and the seafloor increases, which leads to an increase in sinkage, trim and resistance. As the ship travels forward, squat of the ship may occur, stemming from this increase in sinkage and trim. Knowledge of a ship’s squat is necessary when navigating vessels through shallow water regions, such as rivers, channels and harbours. Accurate prediction of a ship’s squat is therefore essential, to minimize the risk of grounding for ships. Similarly, predicting a ship’s resistance in shallow water is equally important, to be able to calculate its power requirements. The key objective of this study was to perform fully nonlinear unsteady RANS simulations to predict the squat and resistance of a model-scale Duisburg Test Case container ship advancing in a canal. The analyses were carried out in different ship drafts at various speeds, utilizing a commercial CFD software package. The squat results obtained by CFD were then compared with available experimental data.

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A numerical investigation of the squat and resistance of ships advancing through a canal using CFD

A geosim analysis of ship resistance decomposition and scale effects with the aid of CFD

The aim of this investigation is to assess the influence of
viscous effects on the predicted hydrodynamic coefficients for a
range of ship-like sections, such as rectangular, triangular, chine
and bulbous. Hydrodynamic coefficients, of added mass or
inertia and fluid damping, for two-dimensional sections
harmonically heaving, swaying and rolling at the undisturbed
free surface are obtained using the ANSYS-CFX11.0 RANS
solver, for a range of frequencies of oscillation. All predictions
are compared with available experimental measurements and
other numerical predictions (potential flow and RANS). It is
concluded from these comparisons that the proposed RANS
approach can offer a better prediction for the hydrodynamic
coefficients when viscous effects become significant, in
particular for sway and roll motions. It is important that a
reliable and systematic approach is adopted for the application
of the unsteady free surface RANS methodology.

A. Que´rard

Papers

Influence of Viscous Effects on the Hydrodynamics of Ship-Like Sections Undergoing Symmetric and Anti-Symmetric Motions, Using RANS