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Old   December 19, 2006, 10:54
Default Global Length
  #1
Andres Bernal
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Hi,

I'm working with an airfoil dimensioned in a unitary way..The Cd looks like very similar but lift don't match reality..

In the .out file I checked a parameter called Global Length which it's very different from the size I decided for the airfoil...this parameter makes the Re number change from 600e3 to 64.2e3...

Does anyone have any Idea?...I have to work with the foil in real size...since i'ts an dimensionless analisys?

Thanks in advance,

Andres.
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Old   December 20, 2006, 08:18
Default Re: Global Length
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Joe
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Make sure you used the correct length unit when importing the mesh into Pre. If you created in mm and imported in m there is obviously going to be a problem.
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Old   December 20, 2006, 11:51
Default Re: Global Length
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Robin
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Hi Andres,

The solver can't determine what the significant length is in a simulation. As a conservative guess, it uses the cube root of the volume of your entire domain. A more agressive guess is to use the maximum dimension of the bounding box.

This length scale is only used to calculate the auto-timescale and generate warnings if the corresponding estimate of the Reynolds number is out of the range of you turbulence model selection. Otherwise it has no influence on your solution.

Regards, Robin
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