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Equilibrium Scour-Depth Prediction around Cylindrical Structures

Tavouktsoglou, NS; Harris, JM; Simons, RR; Whitehouse, RJS; (2017) Equilibrium Scour-Depth Prediction around Cylindrical Structures. Journal of Waterway, Port, Coastal, and Ocean Engineering , 143 (5) , Article 04017017. 10.1061/(ASCE)WW.1943-5460.0000401. Green open access

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Abstract

Offshore gravity base foundations (GBFs) are often designed with complex geometries. Such structures interact with local hydrodynamics, creating an adverse pressure gradient that is responsible for flow and scour phenomena, including the bed shear stress amplification. In this study, a method is presented for predicting clear-water scour around cylindrical structures with nonuniform geometries under the force of a unidirectional current. The interaction of the flow field with the sediment around these complex structures is described in terms of nondimensional parameters that characterize the similitude of water-sediment movement. The paper presents insights into the influence the streamwise depth-averaged Euler number has on the equilibrium scour around uniform and nonuniform cylindrical structures. Here, the Euler number is based on the depth-averaged streamwise pressure gradient (calculated using potential flow theory), the mean flow velocity, and the fluid density. Following a dimensional analysis, the controlling parameters were found to be the Euler number, pile Reynolds number, Froude number, sediment mobility number, and nondimensional flow depth. Based on this finding, a new scour-prediction equation was developed. This new method shows good agreement with the database of scour depths acquired in this study (R2=0.91)(R2=0.91). Measurements of the equilibrium scour depth around nonuniform cylindrical structures were used to show the importance of the Euler number in the scour process. Finally, the importance of the remaining nondimensional quantities with respect to scour was also investigated in this study.

Type: Article
Title: Equilibrium Scour-Depth Prediction around Cylindrical Structures
Open access status: An open access version is available from UCL Discovery
DOI: 10.1061/(ASCE)WW.1943-5460.0000401
Publisher version: https://doi.org/10.1061/(ASCE)WW.1943-5460.0000401
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10044769
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