Cfd modelling to investigate design of awhaleback-Type forecastle for greenwater protection

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2 Citations (Scopus)

Abstract

In extreme weather permanently moored FPSOs may be overtopped by large amounts of greenwater, resulting in damage to deck structures and downtime. Thus, the preliminary design process for FPSOs has often included structural protection to mitigate loads from greenwater on deck and ensure structural integrity of top side structures at the bow in harsh sea conditions. This paper numerically investigates greenwater at the bow of an FPSO fitted with a 'whaleback' or 'duck-bill' shaped forecastle that is represented as an angled extension to the freeboard. In this study, the whaleback forecastle is intended to completely deflect the greenwater flow off the forecastle head. Previously validated numerical models based on OpenFOAM, an open source Computational Fluid Dynamics (CFD) package, are used. The (vertical) run-up height and the forces on the whaleback are analysed based on the CFD results to quantify the effectiveness of the design. It is found that the parameter tan β (FE/γp) that combines the coupled effect of the whaleback geometry and the incoming wave is important for determining the run-up height. The use of this parameter leads to a crude method for fast estimates of the effectiveness of such structures. Increase of the slope of the whaleback forecastle increases the run-up height, thus, increases the horizontal greenwater loading on such structure, however, the direct effect of the slope on the horizontal greenwater loading is found to be limited. An opposite trend is observed for the vertical greenwater loading in which the forecastle slope still plays a significant role even if the effect of run-up height is excluded, as a result of overtopping volume. Additionally, the vertical component of greenwater loading dominates the total greenwater loading on the whaleback forecastle.

Original languageEnglish
Title of host publicationRodney Eatock Taylor Honoring Symposium on Marine and Offshore Hydrodynamics; Takeshi Kinoshita Honoring Symposium on Offshore Technology
Place of PublicationUSA
PublisherASME International
ISBN (Electronic)9780791858882
DOIs
Publication statusPublished - 11 Nov 2019
EventASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2019 - Glasgow, United Kingdom
Duration: 9 Jun 201914 Jun 2019

Publication series

NameProceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE
Volume9

Conference

ConferenceASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2019
Country/TerritoryUnited Kingdom
CityGlasgow
Period9/06/1914/06/19

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