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http://dx.doi.org/10.5574/KSOE.2015.29.1.009

Reynolds number effects on flow over twisted offshore structure with drag reduction and vortex suppression  

Jung, Jae-Hwan (Department of Naval Architecture and Ocean Engineering, Pusan National University)
Yoon, Hyun-Sik (Global Core Research Center for Ships and Offshore Plants, Pusan National University)
Publication Information
Journal of Ocean Engineering and Technology / v.29, no.1, 2015 , pp. 9-15 More about this Journal
Abstract
We investigated the Reynolds number effects on the flow over a twisted offshore structure in the range of 3×103≤ Re ≤ 1 × 104. To analyze the effect of the twisted surface treatment, a large eddy simulation (LES) with a dynamic subgrid model was employed. A simulation of the cylindrical structure was also carried out to compare the results with those of the twisted offshore structure. As Re increased, the mean drag and lift coefficient of the twisted offshore structure increased with the same tendency as those of the cylindrical structure. However, the increases in the mean drag and lift coefficient of the twisted offshore structure were much smaller than those of the cylindrical structure. Furthermore, elongated shear layer and suppressed vortex shedding from the twisted offshore structure occurred compared to those of the cylindrical cylinder, resulting in a drag reduction and suppression of the vortex-induced vibration (VIV). In particular, the twisted offshore structure achieved a significant reduction of over 96% in VIV compared with that of the cylindrical structure, regardless of increasing Re. As a result, we concluded that the twisted offshore structure effectively controlled the flow structures with reductions in the drag and VIV compared with the cylindrical structure, irrespective of increasing Re.
Keywords
Twisted offshore structure; Vortex induced vibration; Large eddy simulation; drag reduction;
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Times Cited By KSCI : 1  (Citation Analysis)
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