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 Toby Wilcox December 10, 1998 13:52

flow over a cylinder

I am a beginner at CFD, just taking my first class actually. The assignment is flow over a cylinder. Can anyone help me??? I am not clear on computing metrics or the PSOR method. Thanks for the help!!

 prasad Patnaik December 11, 1998 14:44

Re: flow over a cylinder

Hi,

Simulating the flow past a circular cylinder is indeed one of the bench mark problems, and is like an "acid test" for any numerical scheme. Ability to simulate the strong Reynolds number dependency associated with the flow is the real crux of the problem. Simulating the flow separation, wake, laminar vortex shedding, transition, turbulent vortex shedding etc. makes the problem more fascinating.

Still hundreds of research papers are being written (both experimental and computational) due to the engineering relevance of the circular geometry. To understand the current state of the art, see the masterly review on this subject by Prof.Williamson (1996) (annual reviews of fluid mechanics, vol.28, pp.477-539)

If it is an assignment problem, the objective should be clear. One of the following could be your aims,

(1). If the flow is highly viscous (Re<5), or inviscid be happy by solving the Laplace equation (Del^2 psi=0), in order to obtain the streamline pattern.

(2). Solve the Navier-Stokes equation, simulate separation behind the body and other wake characteristics. (5 < Re < 250)

(3). Solve the Reynolds averaged N-S equations with an appropriate turbulence model and simulate the turbulent vortex street. (250 < Re < infinity). The quest to find out the most suitable turbulence model is still on! You may have to resort to DNS or LES.

For (3) you may wish to refer the classical paper by Prof.Leschziner (1993) (Journal of Wind Engineering and Industrial aerodynamics, Vol.46&47, pp.37-51)