Plane channel flow

piccinini · March 30, 2009, 20:16

Hello,

I'm a very begginer in OpenFOAM. I'm just trying to simulate a laminar plane channel flow using icoFoam.

I got the conditions from the analytical solution and fvSchemes and fvSolution from Cavity tutorial.
My problem is that Courant number keeps growing until explode.

The setup is attached.

Thanks in advance.

santos · March 31, 2009, 05:00

Hi,

Here are two test-cases that may help you:
http://openfoamwiki.net/index.php/Ma...leSimple2DFlow
http://openfoamwiki.net/index.php/Bl...Flow_Benchmark

Regards,
Jose Santos

piccinini · March 31, 2009, 20:14

Obrigado, Jose Santos!

I've got it to work. I had a problem in the BC and my time step was too high.

sven · June 4, 2009, 17:07

Hi Rodrigo,

I try to solve the same case and I think I also have some problems with my boundary conditions, especially with the one for the outlet. Could you please post your boundary conditions? That would be great! Thanks a lot!

svens · June 5, 2009, 10:17

Hello

I also started with this simple case to collect experiments in OF.

Copied the cavity tutorial and generated new mesh with new BC and initial conditions to solve with icoFoam a 2D channel case.

Now I am wondering - in folder .../case/0/ the dimension definition for pressure p?

-> dimensions [ 0 2 -2 0 0 0 0] -> this is no pressure!?

Anybody an idea about this background?

Thanks & regards

santos · June 5, 2009, 10:33

Hi,

p is the kinematic pressure. If you multiply it by the density, you'll get Pascal units (kg/ms^2).

Regards,
Jose Santos

piccinini · June 5, 2009, 12:19

Hello.

You have my setup attached.
Hope it helps.

sven · June 5, 2009, 15:51

@santos

O.K. p is the kinematic pressure, I understand this. But what should I do if I don't want to set-up a dynamic pressure but a static pressure? If I just change the dimension, I get an error compiling it, which says, that the dimensions don't match. So, what do I have to do if I want to initialize my flowfield with a static pressure?

piccinini · June 5, 2009, 19:47

Hello Sven,

p is the static pressure divided by density (this is what Santos means with kinematic pressure).
You should not change units to set a static pressure, just divide the value by the constant density and set the resulting value.

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March 31, 2009, 05:00		#2
santos Senior Member Jose Luis Santos Join Date: Mar 2009 Location: Portugal Posts: 215 Rep Power: 18	Hi, Here are two test-cases that may help you: http://openfoamwiki.net/index.php/Ma...leSimple2DFlow http://openfoamwiki.net/index.php/Bl...Flow_Benchmark Regards, Jose Santos

March 31, 2009, 20:14		#3
piccinini New Member Join Date: Mar 2009 Location: Sao Jose dos Campos, Brazil Posts: 29 Rep Power: 17	Obrigado, Jose Santos! I've got it to work. I had a problem in the BC and my time step was too high.

June 4, 2009, 17:07		#4
sven Member Sven Winkler Join Date: May 2009 Posts: 70 Rep Power: 16	Hi Rodrigo, I try to solve the same case and I think I also have some problems with my boundary conditions, especially with the one for the outlet. Could you please post your boundary conditions? That would be great! Thanks a lot!

June 5, 2009, 10:17		#5
svens Member Sven Schweikert Join Date: Jun 2009 Posts: 38 Rep Power: 16	Hello I also started with this simple case to collect experiments in OF. Copied the cavity tutorial and generated new mesh with new BC and initial conditions to solve with *icoFoam* a 2D channel case. Now I am wondering - in folder *.../case/0/* the dimension definition for pressure p? -> *dimensions [ 0 2 -2 0 0 0 0]* -> this is no pressure!? Anybody an idea about this background? Thanks & regards

June 5, 2009, 10:33		#6
santos Senior Member Jose Luis Santos Join Date: Mar 2009 Location: Portugal Posts: 215 Rep Power: 18	Hi, p is the kinematic pressure. If you multiply it by the density, you'll get Pascal units (kg/ms^2). Regards, Jose Santos

June 5, 2009, 15:51		#8
sven Member Sven Winkler Join Date: May 2009 Posts: 70 Rep Power: 16	@santos O.K. p is the kinematic pressure, I understand this. But what should I do if I don't want to set-up a dynamic pressure but a static pressure? If I just change the dimension, I get an error compiling it, which says, that the dimensions don't match. So, what do I have to do if I want to initialize my flowfield with a static pressure?

June 5, 2009, 19:47		#9
piccinini New Member Join Date: Mar 2009 Location: Sao Jose dos Campos, Brazil Posts: 29 Rep Power: 17	Hello Sven, p is the static pressure divided by density (this is what Santos means with kinematic pressure). You should not change units to set a static pressure, just divide the value by the constant density and set the resulting value.