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May 31, 2006, 05:55 
flow over a cylinder urgent!

#1 
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hi all, i'm simulating water flow over a circular cylinder, but i find little complete date(experimental or computational) to validate the Cl and Cd and St etc., actually, some author didn't mention the fluid material(water or wind..), by the way, for the two fuids, are these dimensionless quantities such as Cl and Cd and St the same? i think so but find the results at hand are very different...
ANY SUGGESTION ARE APPRECIATED! REGARDS AND THANKS IN ADVANCE! 

May 31, 2006, 06:01 
Re: flow over a cylinder urgent!

#2 
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"are these dimensionless quantities such as Cl and Cd and St the same?"i mean at the same Re number


May 31, 2006, 07:19 
Re: flow over a cylinder urgent!

#3 
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In absense of any airwater interface, matching Re is sufficient for similitude in most cases. However other parameters needed to be matched if you want to account for compressibility (Mach number), surface tension(Weber number), free surface (Froude number).
Flow past cylinders in water is nicely summarised in "Hydrodynamics of Offshore Structures by S.K. Chakrabarti(Publisher: WIT Press (UK); ISBN: 090545166X ). or in Sarpkaya & Isaacson. 

May 31, 2006, 07:21 
Re: flow over a cylinder urgent!

#4 
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Dear Kevin,
The dimensionless quntitites Cd, cl and St number are completely different. These quantities are related to the Reynolds number (irrespective of the Newtonian fluid) ... For a particular Re, these will have the same values of Air and/or water.. In the literature, bulk of data is available for the Cd, Cl, and St for the flow over a circular cylinder .... Goto the http://www.scopus.com and search for the circular cylinder... You can get the basics about these in any fluid dynamics book... 

May 31, 2006, 07:39 
Re: flow over a cylinder urgent!

#5 
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Here are just a selection of some excamples:
flow around a cylinder [1] Ahmad, R.A., 1996, Steadystate numerical solution of the NavierStokes and energy equations around a horizontal cylinder at moderate Reynolds numbers from 100 to 500, Heat Transfer Engg., 17: 3181. [2] Chakraborty, J., Verma, N. and Chhabra, R. P., 2004, Wall effects in the flow past a circular cylinder in a plane channel: a numerical study, Chem. Engng. Processing, 43: 15291537. [3] Coutanceau, M. and Bouard, R., 1977, Experimental determination of the main features of the viscous flow in the wake of a circular cylinder in uniform translation. Part 1: Steady flow, J. Fluid Mech., 79: 231256. [4] Coutanceau, M. and Defaye, J.R., 1991 Circular cylinder wake configurations: a flow visualization survey, Appl. Mech. Rev., 44: 255305. [5] D'Alessio, S. J. D. and Dennis, S. C. R., 1994, A vorticity model for viscous flow past a cylinder, Comp. Fluids, 23: 279293. [6] Dennis, S. C. R. and Chang, G.Z., 1970, Numerical solutions for steady flow past a circular cylinder at Reynolds number up to 100, J. Fluid Mech., 42: 471489. [7] Dennis, S. C. R. and Hudson, J. D., 1995, An $h^4$ accurate vorticityvelocity formulation for calculating flow past circular cylinder, Int. J. Numer. Meth. Fluids, 21: 489497. [8]Dennis, S. C. R., Hudson, J. D. and Smith, N., 1968, Steady laminar forced convection from a circular cylinder at low Reynolds numbers, Phys. Fluids, 11: 933940. [9]Fornberg, B., 1980, A numerical study of steady viscous flow past a circular cylinder, J. Fluid Mech., 98: 819855. [10] Fornberg, B., 1985, Steady viscous flow past a circular cylinder up to Reynolds number 600, J. Comp. Phys., 61: 297320. [11] Ding, H., Shu, C., Yeo, K. S. and Xu, D., 2004, Simulations of incompressible viscous flows past a circular cylinder by hybrid FD scheme and meshless least squarebased finite difference scheme, Comput. Methods Appl. Mech. Engng., 193: 727744. [12] Hamielec, A. E. and Raal, J. D., 1969, Numerical studies of viscous flow around circular cylinders, Phys. Fluids, 12: 1117. [13] Kawaguti, M. and Jain, P., 1966, Numerical study of a viscous flow past a circular cylinder, J. Phys. Soc. Jpn., 21: 20552062. [14] Sucker, D. and Brauer, H., 1975, Fluiddynamik bie quer angestromten Zylindern, Warme and Stoffubertagaung, 8: 149158. [15] Takami, H. and Keller, H. B., 1969, Steady twodimensional viscous flow of an incompressible fluid past a circular cylinder, HighSpeed Computing in Fluid Dynamics The Phys. Fluids Supplement II, 12: 5156. M.M. Zdravkovich, Flow Around Circular Cylinders, Vol. 1 Fundamentals, Oxford University Press, 1997 [2] M.M. Zdravkovich, Flow Around Circular Cylinders, Vol. 2 Applications, Oxford University Press, 2003 [1] Norberg, C. (2003). Fluctuating lift on a circular cylinder: Review and new measurements, Journal of Fluids and Structures 17 (1), pp. 5796 29 [2] Norberg, C. (2001). Flow around a circular cylinder: Aspects of fluctuating lift, Journal of Fluids and Structures 15 (34), pp. 459469 [3]Norberg, C. (1994). Experimental investigation of the flow around a circular cylinder: influence of aspect ratio, Journal of Fluid Mechanics 258, pp. 287316 96 [4] Norberg, C., Sunden, B. J. (1987). Turbulence and Reynolds number effects on the flow and fluid forces on a single cylinder in cross flow, FLUIDS & STRUCT. 1 (3 , Jul. 1987), pp. 337357 9 [5] Norberg, C. (1985). INTERACTION BETWEEN FREESTREAM TURBULENCE AND VORTEX SHEDDING FOR A SINGLE TUBE IN CROSSFLOW, Journal of Wind Engineering and Industrial Aerodynamics 23 (13), pp. 501514 

May 31, 2006, 09:03 
Re: flow over a cylinder urgent!

#6 
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sincerely thank you two, ramp and Rudi, ur words are absolutely useful!


May 31, 2006, 15:26 
Re: flow over a cylinder urgent!

#7 
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Check the following:
http://www.cfdonline.com/Forum/main...cgi?read=44651 http://www.cfdonline.com/Forum/main...cgi/read/40050 http://www.cfdonline.com/Search/cgi...words=circular%20cylinder;page=1 

June 8, 2006, 01:19 
Re: flow over a cylinder urgent!

#8 
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Hi,
Cd, Cl and St are nondimensionnal numbers. But be aware that you can find different definitions of these coefficients (above all for the area to take into account) according to the author. In Fluent, I know that: Cd=drag force/(0.5*rho*velocity^2*area) where rho, velocity and area have to be specified in the reference values panel. For the formulation of Cl, I suggest you to ask fluent a force report and try to find the relation between the lift force and coefficients. 

August 11, 2015, 13:00 

#9 
New Member
nabaouia
Join Date: Aug 2014
Posts: 14
Rep Power: 3 
well I think that you must to enter the value of the area (projeted area for exp : circualr cylinder take the daimeter ) .go to REPORT >REFERENCE VALUES area= lentgh IN THIS CASE


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