Evaluation of hull flow quality
General information
Already without viscous effects (in panels codes like RAPID) hull lines can be optimized for wave making. However, especially for aft ship design RANS codes are extremely useful. RANS calculations can contribute to hull line development in several ways; analysis of the boundary layer built up, hull pressure distribution, limiting streamlines on the hull and 3D bulk flow can help to understand the interaction between geometry and flow. Furthermore the wake field at the propeller position can be extracted and used for further analysis or propeller design.

Example: twin gondola
An example where RANS calculations can play an important role is in hull line development of a twin gondola aft ship. Below two versiosn of the same ship are shown (old and new), with a visualisation of the flow below each variant. Where for the old shape a flow separation area (white region) is observed aft of the transom, with a slight change of the gondola the flow separation vanishes and the flow is nicely aligned with the gondola.

Both calculations were performed for deep water. For shallow water the water supply from below is partly blocked and more water is transported from the side of the ship. Especially for twin gondola ships this can result in significant changes to the flow pattern. Below the situation for the new gondola in shallow water is shown with (right) and without (left) the effect of propeller action. It is clear that these aspects play an important role in determining the quality of a hull shape.

Recent Papers:
Multi-Objective Surrogate Based Hull-Form Optimization Using High-Fidelity RANS Computations
Scholcz, T.P. and Veldhuis, C.H.J., VII International Conference on Computational Methods in Marine Engineering (MARINE2017), Nantes, France, 2017

Optimization of a ship with a large diameter propeller
Ploeg, A. van der, Bles, G. van der, and Zelderen, J. van, 19th Numerical Towing Tank Symposium (NuTTS), St. Pierre d'Oléron, France, 2016

Viscous Free-Surface Power Predictions For Self-Propulsion Using A Hybrid RANS-BEM Coupling Procedure (PARNASSOS-PROCAL)
Starke, B. S., Tokyo 2015, A Workshop on CFD in Ship Hydrodynamics, Tokyo, Japan, 2015

Integrated design of asymmetric aftbody and propeller to maximize energy efficiency
Rueda, L. and Dang, J., RINA Energy Efficient Ships, Rotterdam, The Netherlands, 2015

Optimization of the STREAMLINE tanker using RANS/FS computations
Van der Ploeg, A., NUTTS 2014, Gothenburg, Sweden, 2014

Promising Hydrodynamic Improvements For Inland Vessels
Van der Meij, K.H. and Raven, H.C., European Inland Waterway Navigation Conference, Budapest, Hungary, 2014

A computational study of shallow-water effects on ship viscous resistance
Raven, H.C., 29th Symposium on Naval Hydrodynamics (ONR), Gothenburg, Sweden, 2012

Object Functions for Optimizing a Ship’s Aft Body
Ploeg, A. van der, 11th International Conference on Computer and IT Applications in the Maritime Industries (COMPIT), Liège, Belgium, 2012

Prediction Of The Transom Flow Regime With Viscous Free Surface Computations
Ploeg, A. van der and Starke, A.R., IV International Conference on Computational Methods in Marine Engineering (ECCOMAS MARINE), Lisbon, Portugal, 2011

Trim wedge optimization using RANS/FS
Starke, A.R., Ploeg, A. van der, and Veldhuis, C.H.J., RINA Developments in Marine CFD, 2011

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