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

Title & Authors
Reynolds number effects on flow over twisted offshore structure with drag reduction and vortex suppression
Jung, Jae-Hwan; Yoon, Hyun-Sik;

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;
Language
Korean
Cited by
References
1.
Ahmed, A., Bays-Muchmore, B., 1992. Transverse Flow over a Wavy Cylinder. Physics of Fluids A, 4, 1959-1967.

2.
Bishop, R.E.D., Hassan, A.Y., 1964. The Lift and Drag Forces on a Circular Cylinder in a Flowing Fluid. Proceedings of The Royal Society A, 277(1368), 32-50.

3.
Breuer, M., 1998. Large Dddy Simulation of the Subcritical Flow Past a Circular Cylinder: Mumerical and Modeling Aspects. International Journal for Numerical Methods in Fluids, 28, 1281-1302.

4.
Breuer, M., 2000. A Challenging Test Case for Large Eddy Simulation: High Reynolds Number Circular Cylinder. International Journal of Heat and Fluid Flow, 21, 648-654.

5.
Chyu, C.K., Rockwell, D., 1996. Near-wake Structure of an Oscillating Cylinder: Effect of Controlled Shear-layer Vortices. Journal of Fluid Mechanics, 322, 21-49.

6.
Dong, S., Karniadakis G.E., Ekmekci, A., Rockwell, D., 2006. A Combined Direct Numerical Simulation-particle Image Velocimetry Study of the Turbulent Near Wake. Journal of Fluid Mechanics, 569, 185-207.

7.
Germano, M., Piomelli, U., Moin, P., Cabot, W.H., 1991. A Dynamic Subgrid-scale Eddy Viscosity Model. Physics of Fluids A, 3, 1760-1765.

8.
Gopalkrishnan, R., 1993. Vortex-induced Forces on Oscillating Bluff Cylinders. PhD thesis, Department of Ocean Engineering, MIT, Cambridge, MA, USA.

9.
Jordan, S.A. and Ragap, S.A., 1998. A Large-eddy Simulation of the Near Wake of a Circular Cylinder, Journal of Fluids Engineering. 120(2), 243-252.

10.
Jordan, S.A., 2002. Investigation of the Cylinder Separated Shear-layer Physics by Large-eddy Simulation. International Journal of Heat and Fluid Flow. 23(1), 1-12.

11.
Jung, J.H., Yoon, H.S., Choi, C.Y., Chun, H.H., Park, D.W., 2012. Large Eddy Simulation of Flow around Twisted Offshore Structure with Drag Reduction and Vortex Suppression. Journal of the Society of Naval Architects of Korea, 49(5), 440-446.

12.
Keefe, R.T., 1962. Investigation of the Fluctuating Forces Acting on a Stationary Circular Cylinder in a Subsonic Stream and of the Associated Sound Field. The Journal of the Acoustical Society of America, 34, 1711-1714.

13.
Lam, K., Lin, Y.F., 2008. Large Eddy Simulation of Flow Around Wavy Cylinders at a Subcritical Reynolds Number. International Journal of Heat and Fluid Flow, 29, 1071-1088.

14.
Lam, K., Wang, F.H., Li, J.Y., So, R.M.C., 2004a. Experimental Investigation of the Mean and Fluctuating Forces of Wavy(varicose) Cylinders in a Cross-flow. Journal of fluids and structures, 19, 321-334.

15.
Lam, K., Wang, F.H., So, R.M.C., 2004b. Three-dimensional Nature of Vortices in the Near Wake of a Wavy Cylinder. Journal of fluids and structures, 19, 815-833.

16.
Lee, S.J., Nguyen, A.T., 2007. Experimental Investigation on Wake Behind a Wavy Cylinder Having Sinusoidal Cross-sectional Area Variation. Fluid Dynamics Research, 39, 292-304.

17.
Moeller, M.J., 1982. Measurement of Unsteady Forces on a Circular Cylinder in Cross Flow at Subcritical Reynolds Numbers. Ph.D. Thesis, Department of Ocean Engineering, MIT, Cambridge, MA, USA.

18.
Moeller, M.J., Leehey, P., 1984. Unsteady Forces on a Cylinder in Fross Flow at Subcritical Reynolds Numbers. In ASME Symposium on Flow-induced Vibrations (ed. M. P. Paidoussis, O. M, Griffin & M. Sevik), New Orleans, ASME, New York 1, 57-71.

19.
Nebres, J., Batill, S., Nelson, R., 1993 Flow about Yawed, Stranded Cables. Experiments in Fluids, 14, 49-58.

20.
Norberg, C., 1987. Effects of Reynolds Number and a Low-intensity Freestream Turbulence on the Flow around a Circular Cylinder, Publ. 87/2. Department of Applied Thermodynamics and Fluid Mechanics. Chalmers Univrsity of Technology.

21.
Norberg, C., 1998. LDV-measurements in the Near Wake of a Circular Cylinder. Proceeding of The ASME Fluids Engineering Div. Summer Meeting, Washington, DC, Paper 4. Also ASME, FEDSM 98-5202.

22.
Norberg, C., 2003. Fluctuating Lift on a Circular Cylinder: Review and New Measurements. Journal of Fluids and Structures, 17, 57-96.

23.
Prasad, A., Williamson, C.H.K., 1997. Three-dimensional Effects in Turbulent Bluff-body Wakes. Journal of Fluid Mechanics, 343, 235-265.

24.
Tadrist, H., Martin, R., Tadrist, L., Seguin, P., 1990. Experimental Investigation of Fluctuating Forces Exerted on a Circular Cylinder Tube (Reynolds Numbers from 3000 to 30,000). Physics of Fluids A, 2, 2176-2182.

25.
Unal, M.F., Rockwell, D., 1988. On Vortex Formation from a Cylinder. Part 1. The Initial Instability. Journal of Fluid Mechanics, 190, 491-512.

26.
West, G.S., Apelt, C.J., 1993. Measurements of Fluctuating Pressures and Forces on a Circular Cylinder in the Reynolds Number range $10^4$ to 2.5$\times$$10^5$. Journal of fluids and structures, 7, 227-244.

27.
White, F.W., 1974. Viscous Fluid Flow. McGraw-Hill, New York.

28.
Williamson, C.H.K., 1996. Vortex Dynamics in the Cylinder Wake. Annual Review of Fluid Mechanics, 28, 477-539.

29.
Yoon, H.S., Balachandar, S., Ha, M.Y., 2009. Large Eddy Simulation of Flow in an Unbaffled Stirred Tank for Different Reynolds Numbers. Physics of fluids, 21, 1-16.

30.
Zhou, J., Adrian, R J., Balachandar, S., Kendall, T.M., 1999. Mechanisms for Generating Coherent Packets of Hairpin Vorticies in Channel Flow, Journal of Fluid Mechanics, 387, 353-396.