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-   -   Different Drag coefficient (http://www.cfd-online.com/Forums/fluent/116918-different-drag-coefficient.html)

babak.mahjoub April 28, 2013 08:26

Different Drag coefficient
 
Hi everybody.

I am trying to study the flow over a circular cylinder.

Simply put, the problem is I get different drag coefficient (and other coefficients as well) with the same Reynolds number,

Of course each time I change the diameter and velocity, but the Reynolds number remains the same, I though it is supposed to get me the same result.

For instance:

Fluid is air at 20 Celsius, transient flow, 2d, laminar

D= 0.16 u= 0.0095 => Re=100 Drag co. = 0.2323
D= 0.016 u= 0.095 => Re=100 Drag co. = 0.0183
While I find in literatures that this value must be around 1.2 :eek:

If Reynolds number is not the only determinant factor, how do I validate my data with privious studies, as they just mentiones Reynolds number, not the inlet velocity

Thanks

RodriguezFatz April 29, 2013 08:34

From what I learned from previous threads here, it could be that your domain is too small, i.e. the distance from inlet to cylinder is too small or the distance from cylinder to outlet. Can you post a picture of your domain?


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