Study of Flow Characteristics around a NearWall Circular Cylinder Subjected to a Steady CrossFlow

Mohammad Amin Salehi ^{} , Said Mazaheri , Mohammad Hossein Kazeminezhad 
student 

Abstract: (406 Views) 
Threedimensional RANS simulations are employed numerically to study flow characteristics around a nearwall circular cylinder for varying gaptodiameter (G/D) ratios (Where G is the gap between the cylinder and the wall and D is the cylinder diameter) and at Reynolds numbers from 100 to 3900. Pressure distribution around the circular cylinder, base pressure magnitude, separation and stagnation angles, force coefficients and Strouhal numbers were calculated and compared for all of the cases. Inception of vortex shedding can be seen when a sudden decrease in the maximum of positive pressure coefficient occurs. Vortex shedding mechanism and possibility of suppression further investigated via comparison of swirling strength in upper and lower vortex regions through parameter Λ, which signifies vortical activity and balance with respect to the wake centerline and also the flow type parameter, λ, representing the extensional strain dominance in the wake flow and gap flow. Vortex shedding suppression observed for the cases with the high unbalance vorticity content in the vortex regions, namely for Λ ≥ 2. 

Keywords: pressure distribution, force coefficients, separation angle, stagnation angle, vortex shedding suppression 

FullText [PDF 2380 kb]
(149 Downloads)

Type of Study: Research 
Subject:
Marine Hydrodynamics Received: 2018/01/7  Accepted: 2018/03/6  Published: 2018/05/5





References 
1. Batham, J.P., (1973). Pressure distributions on circular cylinders at critical Reynolds numbers. Journal of Fluid Mechanics, Vol.57, p.209–228 [ DOI:10.1017/S0022112073001114] 2. Bearman P.W. & Zdravkovich M.M., (1978). Flow around a circular cylinder near a plane surface, Journal of Fluid Mechanics, Vol.89, p.3347. [ DOI:10.1017/S002211207800244X] 3. Zdravkovich M.M., (1985). Forces on a circular cylinder near a plane wall, Applied Ocean Research Vol.7, p.197201. [ DOI:10.1016/01411187(85)900264] 4. Buresti, G., and Lanciotti, A., (1992). Mean and ﬂuctuating forces on a circular cylinder in crossﬂow near a plane surface, Journal of Wind Engineering and Industrial Aerodynamics, Vol.41(1–3), p.639–650. [ DOI:10.1016/01676105(92)90476Q] 5. Oner, A.A., Kirkgoz, M.S., Akoz, S., (2008). Interaction of a current with a circular cylinder near a rigid bed, Journal of Ocean Engineering, Vol.35, p.14921504. [ DOI:10.1016/j.oceaneng.2008.06.005] 6. Lei C., Cheng L., Kavanagh K., (1999). Reexamination of the effect of a plane boundary on force and vortex shedding of a circular cylinder, Journal of Wind Engineering and Industrial Aerodynamics, Vol.80(3), p.163–286. [ DOI:10.1016/S01676105(98)002049] 7. Price, S.J., Sumner, D., Smith, J.G., Leong, K., Paidoussis, M.P., (2002). Flow visualization around a circular cylinder near to a plane wall, Journal of Fluids and Structures Vol.16, p.175–191. [ DOI:10.1006/jfls.2001.0413] 8. Wang, X. K., Tan, S. K., (2008). Nearwake ﬂow characteristics of a circular cylinder close to a wall, Journal of Fluids and Structures, Vol.24(5), p.605–627. [ DOI:10.1016/j.jfluidstructs.2007.11.001] 9. Lin W. J., Lin C., Hsieh S. C, Dey S., (2009). Flow characteristics around a circular cylinder placed horizontally above a plane boundary, Journal of Engineering Mechanics, Vol.135, p.697716. [ DOI:10.1061/(ASCE)07339399(2009)135:7(697)] 10. Dipankar, A., Sengupta, T. K. (2005). Flow past a circular cylinder in the vicinity of a plane wall, Journal of Fluids and Structures, Vol.20(3), p.403–423. [ DOI:10.1016/j.jfluidstructs.2005.01.001] 11. Sarkar, S., Sarkar, S. (2010). Vortex dynamics of a cylinder wake in proximity to a wall, Journal of Fluids and Structures Vol.26(1), p.19–40. [ DOI:10.1016/j.jfluidstructs.2009.08.003] 12. He, G. S., Wang, J. J., Pan, C., Feng, L. H., Gao, Q., Rinoshika, A, (2017). Vortex dynamics for flow over a circular cylinder in proximity to a wall, Journal of Fluid Mechanics. Vol.812, p.698–720. [ DOI:10.1017/jfm.2016.812] 13. Menter F. R., (1994). Twoequation eddyviscosity turbulence models for engineering applications. AIAA Journal, Vol.32(8), p.1598–605. [ DOI:10.2514/3.12149] 14. Schlichting, H., Gersten, K. (2017). BoundaryLayer Theory. Springer, Heidelberg. [ DOI:10.1007/9783662529195] 15. Cao, H., Wan, D., (2010). Application of OpenFOAM to Simulate ThreeDimensional Flows past a Single and Two Tandem Circular Cylinders, Proceedings of the Twentieth International Offshore and Polar Engineering Conference Beijing, China, June 2025, 2010. 16. Sengupta, T.K., De, S., Sarkar, S., (2003). Vortexinduced instability of incompressible wallbounded shear layer. Journal of Fluid Mechanics Vol.493, p.277–286. [ DOI:10.1017/S0022112003005822]


