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-   -   Set up a wind velocity for an experiment. (http://www.cfd-online.com/Forums/main/105741-set-up-wind-velocity-experiment.html)

 bitacovir August 8, 2012 02:20

Set up a wind velocity for an experiment.

I'm using ElmerGUI as cfd software and I want to set up the velocity of the flow (wind). I understand this instruction of a tutorial is to create a parabolic profile of the flow in velocity 1...

Model
BoundaryCondition
Name = Inlet
Navier-Stokes
Velocity 1 = Variable Coordinate 2; Real MATC "4* 1.5 * tx * (0.41-tx)/0.41^2"
Velocity 2 = 0.0
New

I understand that this equation (for a experiment 2D in a channel) "4* 1.5 * tx * (0.41-tx)/0.41^2" represents this profile:
http://i.imgur.com/TOwLm.jpg

I would need a equation for this kind of profile: That is for a curve of a boundary layer. Someone know how will be the equation for this curve to work with Elmer?
http://i.imgur.com/JvEMx.jpg

 Rami August 15, 2012 08:17

Hi Bitacovir,

I have no access to Elmer manuals at the moment, so forgive me if the syntax is not exact.

Suppose - for example - that your axial velocity, U, is parabolic in the transverse coordinate, y, with
U = 1*y^2 + 2*y + 3
then use

\$A = 1.
\$B = 2.
\$C = 3.
Velocity 1 = Variable Coordinate 2; Real MATC " \$A * tx^2 + \$B * tx + \$C"

Sorry if I omitted a dollar or two...
Rami

 bitacovir August 16, 2012 05:51

Quote:
 Originally Posted by Rami (Post 377202) Hi Bitacovir, I have no access to Elmer manuals at the moment, so forgive me if the syntax is not exact. Suppose - for example - that your axial velocity, U, is parabolic in the transverse coordinate, y, with U = 1*y^2 + 2*y + 3 then use \$A = 1. \$B = 2. \$C = 3. Velocity 1 = Variable Coordinate 2; Real MATC " \$A * tx^2 + \$B * tx + \$C" Sorry if I omitted a dollar or two... Rami
Dear Rami:

Thanks a lot. I going to try this suggestion. Currently I was using http://www.comflow.nl/ that is easier to set up Inlet conditions such as profile of wind.

Here one example that I was doing...
http://i.imgur.com/NM8Y0.gif

Kind Regards.

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