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!

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

In absense of any air-water 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.

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...

Here are just a selection of some excamples:

flow around a cylinder

[1] Ahmad, R.A., 1996, Steady-state numerical solution of the Navier-Stokes and energy equations around a horizontal cylinder at moderate Reynolds numbers from 100 to 500, Heat Transfer Engg., 17: 31-81.

[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: 1529-1537.

[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: 231-256.

[4] Coutanceau, M. and Defaye, J.-R., 1991 Circular cylinder wake configurations: a flow visualization survey, Appl. Mech. Rev., 44: 255-305.

[5] D'Alessio, S. J. D. and Dennis, S. C. R., 1994, A vorticity model for viscous flow past a cylinder, Comp. Fluids, 23: 279-293.

[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: 471-489.

[7] Dennis, S. C. R. and Hudson, J. D., 1995, An $h^4$ accurate vorticity-velocity formulation for calculating flow past circular cylinder, Int. J. Numer. Meth. Fluids, 21: 489-497.

[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: 933-940.

[9]Fornberg, B., 1980, A numerical study of steady viscous flow past a circular cylinder, J. Fluid Mech., 98: 819-855.

[10] Fornberg, B., 1985, Steady viscous flow past a circular cylinder up to Reynolds number 600, J. Comp. Phys., 61: 297-320.

[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 square-based finite difference scheme, Comput. Methods Appl. Mech. Engng., 193: 727-744.

[12] Hamielec, A. E. and Raal, J. D., 1969, Numerical studies of viscous flow around circular cylinders, Phys. Fluids, 12: 11-17.

[13] Kawaguti, M. and Jain, P., 1966, Numerical study of a viscous flow past a circular cylinder, J. Phys. Soc. Jpn., 21: 2055-2062.

[14] Sucker, D. and Brauer, H., 1975, Fluiddynamik bie quer angestromten Zylindern, Warme- and Stoffubertagaung, 8: 149-158.

[15] Takami, H. and Keller, H. B., 1969, Steady two-dimensional viscous flow of an incompressible fluid past a circular cylinder, High-Speed Computing in Fluid Dynamics The Phys. Fluids Supplement II, 12: 51-56.

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. 57-96 29

[2] Norberg, C. (2001). Flow around a circular cylinder: Aspects of fluctuating lift, Journal of Fluids and Structures 15 (3-4), pp. 459-469

[3]Norberg, C. (1994). Experimental investigation of the flow around a circular cylinder: influence of aspect ratio, Journal of Fluid Mechanics 258, pp. 287-316 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. 337-357 9

[5] Norberg, C. (1985). INTERACTION BETWEEN FREESTREAM TURBULENCE AND VORTEX SHEDDING FOR A SINGLE TUBE IN CROSS-FLOW, Journal of Wind Engineering and Industrial Aerodynamics 23 (1-3), pp. 501-514

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

Check the following:

http://www.cfd-online.com/Forum/main...cgi?read=44651

http://www.cfd-online.com/Forum/main...cgi/read/40050

http://www.cfd-online.com/Search/cgi...words=circular%20cylinder;page=1

Hi,

Cd, Cl and St are non-dimensionnal 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.

[bia]

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