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-   -   turbulent pipe flow (http://www.cfd-online.com/Forums/fluent/37446-turbulent-pipe-flow.html)

John August 2, 2005 04:44

turbulent pipe flow
 
How do i calculate boundary conditions for turbulence at the inlet and outlets? I have the reynolds numbers at these boundaries, and the diameters for the pipes.

Reading the user guide, I am assuming i use the turbulence intensity and length scale to define the turbuence. Does anyone have some good approximating formula's for these parameters?

My model involves a compressible gas flow at 6000kPa (within a natural gas transmission pipeline).

Thanks.

pUl| August 2, 2005 10:52

Re: turbulent pipe flow
 
Intensity (Refer Fluent manual for calculating turbulence intensity -> http://www.fluentusers.com/fluent/do...e180.htm#26619) and Hydraulic diameter (= diameter of pipe for a cylinder even if modeled in 2D).

Swarup August 2, 2005 13:00

Re: turbulent pipe flow
 
it is difficult to calculate them accurately. a thumb rule says that moderate intensity of 5% should be used. at the upper range, it can be 15-20%. i am not sure about length scale range.

Swarup.


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