Feature 1 | CFD AND HYDRODYNAMICS
Figure 9: Comparison of predicted normalised side forces and yaw moments (VIRTUE – WP 3).
yielded satisfactory results for standard vessels in the past; today’s focus lies on the simulation of extreme situations and extreme ship designs. FreSCo+
is now
applied to the analysis of ship motion behaviour using a 6 DoF approach. Te following example shows results from the simulation of a container vessel in head seas with good balance between the experiment and numerical results.
Summary Today, FreSCo+
Figure 10: Predicted streamlines and hull pressure distribution (left) and axial flow field velocity (right) for a drift angle of 30degs.
has been successfully
applied to a wide range of typical shipbuilding and maritime applications during the routine work at HSVA. Accurate free surface predictions as well as the numerical propulsion test, make FreSCo+
the tool of choice for Figure 11: Ship motion simulation - Container vessel in head seas.
showed that it is a valuable means for the prediction of manoeuvring performance at the design stage of a new ship. Besides, the overall amount of flow field information yielded (see the predicted streamlines and hull pressure distribution for a yaw angle of 30degs) provide deeper insight into the mechanisms and will help to suggest improvements for critical cases.
Figure 12: Comparison of pitch motion simulation – FreSCo+
(green) and experiment
(red). Present research aims at the prediction of vessel behaviour in extreme conditions including rogue waves.
In a workshop with six participants
using different flow codes, HSVA’s FreSCo+
predictions again are among the
best submitted results. Te code proved to be accurate, fast and versatile and
42
Seakeeping predictions and ship stability Safety is now acknowledged to be a design driver and key to sustaining the leadership with technologically advanced ships. Ship stability in a seaway is a prime element of an integral safety assessment of new and more unconventional vessels, which stretch the limits of traditional evaluation methods. Where former panel code or strip method based numerical tools
ambitious ship design applications and further challenging analysis tasks. Recent research of the joint development group at TUHH and HSVA will further enhance capabilities and functionality of the code to meet new requirements arising from offshore applications and stability / safety considerations. At HSVA a full range of FreSCo+
based services is offered in
routine projects for the benefit of our customers. NA
References: 1 Pereira, F., Salvatore, F., Di Felice, F. (2004). ‘Measurement and Modelling of Propeller Cavitation in Uniform Inflow.’ Journal of Fluids Engineering, Vol. 126, July 2004, pp. 671-679. p27 ff.
2 H. Streckwall: “Eine instationäre Vortex-Lattice Methode für den Schiffspropeller”, Proceedings Rostocker Schiffstechnisches Symposium ‚91, Rostock, 1991.
3 Chao, K.Y.: “Vereinfachte Methode zur Leistungsprogonose unter genauer Erfassung der Wechselwirkung zwischen Schiffsrumpf, Ruder und Propeller”, HSVA Bericht Nr. 1637 (2000) (BMBF-Förderkennzeichen 18S0155)
4 Chao, K.Y.:“Numerical Propulsion Tests”, Ship Technology Research (Schifechnik), Vol. 48, No.2, (June 2001)
The Naval Architect July/August 2010
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