Effect of separation vortices on wave-induced sway force and yaw moment acting on a ship running in stern quartering waves

For accurately evaluating the risk of broaching for a ship in stern quartering waves, the wave forces calculated with a slender body theory under the low encounter frequency assumption are often corrected empirically with the help of captive model experiment or computational fluid mechanics (CFD). H...

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Bibliographic Details
Published in:Journal of marine science and technology 2022-03, Vol.27 (1), p.203-213
Main Authors: Htet, Thet Zaw, Umeda, Naoya, Toda, Yasuyuki, Hashimoto, Hirotada, Omura, Tomoyuki, Stern, Frederick
Format: Article
Language:English
Subjects:
Automotive Engineering
Broaching
Computer applications
Engineering
Engineering Design
Engineering Fluid Dynamics
Fluid mechanics
Hydrodynamics
Mechanical Engineering
Offshore Engineering
Original Article
Slender bodies
Theories
Vortices
Wave forces
Yawing
Yawing moments
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Summary:For accurately evaluating the risk of broaching for a ship in stern quartering waves, the wave forces calculated with a slender body theory under the low encounter frequency assumption are often corrected empirically with the help of captive model experiment or computational fluid mechanics (CFD). However, the hydrodynamic explanation of such empirical correction was not sufficient so far. Thus, this paper attempts to provide an answer to this deficiency. First, we visualise the vortices shed from the hull surface using existing CFD results for the ONR tumblehome topside vessel. Then we extend Hamamoto’s slender body theory, in which the interaction between the shed vortex and the hull sections is taken into account for calm water, to the case in astern waves and apply it to the current case by using the CFD-based vortices strength and position. As a result, it is confirmed that additional hydrodynamic forces due to vortices shed from the hull surface other than transom are a major component of the empirical correction for supplementing the conventional slender body theory, which covers the Froude–Krylov force and hydrodynamic lift from the transom.
ISSN:0948-4280
1437-8213
DOI:10.1007/s00773-021-00826-w