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-   -   Openfoam friction coefficient differences. (http://www.cfd-online.com/Forums/openfoam-post-processing/84769-openfoam-friction-coefficient-differences.html)

Peter88 February 8, 2011 11:07

Openfoam friction coefficient differences.
 
He,

I am investigating a pipe flow which has the following dimensions.

Length 30m, diameter 0.1. A uniform inlet velocity of 10m/s was used as a boundary with a pressure oulet of 0Pa.

After simulation.
I checked the Yplus.
The pressure at the inlet is 285Pa
dp/dx is -9.433.

With the following formule i calculated the friction coefficient:

dp/dx=(-0.5 x rho x 10 x cf) /D

cf=0.0154 or something like that. And I would like to have a friction factor of 0.019.

Because that is the friction factor that I should have if I fill in my Re, for a smooth pipe situation. I looked this up in a applied fluid dynamic handbook, there is a graph with the friction coefficient vs reynolds number.

Anybody has an idea of an increase in pressure, so that my dp/dx becomes 11.7 and therefore my friction factor 1.9?

Thank Peter


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