# constant flowrate in fluid with windFoam

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November 10, 2010, 09:23
constant flowrate in fluid with windFoam
#1
New Member

Oli
Join Date: Apr 2009
Posts: 27
Rep Power: 10
Hello Foamers!

I'm trying to set a constant flowrate in a specific fluid area.
It should work like a momentum source.
I'm trying to use simpleWindFoam but I'm not sure, if I understand simpleWindFoam the right way.

The Model is a simple duct with 2 pressure-outlets at the end.
The Area. which should work as momentum source, is selected by a cellset.
The inital conditions is a zero-velocity-field (picture "initialisation.jpg")

Now i want to define a constant flowrate or velocity in the marked fluidcells.
So the source should suck the fluid from the left side und blows it to the right (picture "result.jpg")
We can do this in STARCD very easily.

So in
OpenFOAM-1.7.0/src/finiteVolume/cfdTools/general/fieldSources/basicSource/actuationDiskSource
I found in the file actuationDiskSourceTemplates.C the equation

T = 2.0*rho*diskArea_*mag(U1)*a/(1.0 - a)

by setting Cp to 0.5 and Ct to 1.0, a and (1.0-a) can be ignored.

T = 2.0*rho*diskArea_*mag(U1)*a [kg/s]

So my intension was, to define a velocity for the fluid cells in the marked area with setFields. For example U = ( 5 0 0) m/s, rho=1, diskArea = 0.1

--> T = 1 kg/s

Should this work that way?
Or is there another opportunity?
I don't want to use directMapped or cyclic.

Thanks and best regards!

olhe
Attached Images
 initialisiation.jpg (51.9 KB, 34 views) result.jpg (49.9 KB, 33 views)

 November 10, 2010, 21:19 #2 Member   Robin Gilbert Join Date: Jan 2010 Posts: 66 Rep Power: 9 try using channelFoam and modify the solve u r using based on channelFoam. I tried something like that and it worked fine....

 November 11, 2010, 06:40 #3 New Member   Oli Join Date: Apr 2009 Posts: 27 Rep Power: 10 Thank you for your reply! Unfortunately I'm not so good in coding yet. Do you have an example of your modified solver? Perhaps a simple one like simpleFoam? Thank you very much and best regards olhe

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