Free convection
 

Hey guys,

I try to simulate a verticale plate in the atmosphere. For this case I create a box and on one side I add a small plate. Around I want to have everywhere atmosphere (air). The plate should have an temperature from 333 K and the atmosphere should have 293 K.

However I get always worst results. I think my boundarys are wrong.

Have somebody fixed this issue and can sent me a example case or tell me the right boundarys in the T, U, p_rgh and P file for my plate and the atmosphere?


regards
Michael

Please furnish more details
 

Can you please furnish more details like what is the element size, number, layers, etc?

Hello sengerandu,

thank you for your reply.

My first cell ist 0,014 mm thick and the gradient ist 20.

Now I've changed my case. I have a horizontal zylinder. In the vertical I used a symmetrPlane to reduce my mesh. Also I simulate 2D now.

T-File:
Is on atmosphere "inletOutlet" and on the wall ist "fixedValue".

U-File:
For atmosphere I use "pressureInletOutletVelocity" and for the wall I use "fixedValue".

P-File ist "calculated"


I think there ist a problem with the p_rgh file. Here I tried a lot of values:
fixedValue, fixedFluxPressure, zeroGradient, totalPressure for the wall and atmosphere.
And my flow pattern look like worse!


Best wishes
Michael

Micha69822,

¿did you get your case runnin? You are trying to simulate an open environment aren´t you? So am I, but I dont get any physical results....
It must be the boundary conditions...

Cristina

Hi,

yes I did.

My failure was the p_rgh File. The bottom has to defined as "totalPressure" and the atmosphere around has to "inletOutlet". The other BC's the same as I described.

And now I get the right solutions!

Hi Micha69822,

Which solver are you using? buoyantBoussinesqSimpleFoam? I am trying with SimpleFoam, but I do not find the right BC.
I have flow over a ground in atmospheric conditions.... very simple: inlet (constant wind velocity) outlet, sides and Sky and then the ground....
As you recommended, I am using totalPressure in the outet but I dont get good results...
Can you post your BC more detailed? I also attach you my case, maybe you can help me...

thanks!

Cristina

Hi cristina,

I can't work with your files because I use OpenFOAM Version 2.3.0.
But I see in your blockMeshDict that you have defined all faces as wall. For atmosphere you need patch but there is a different in the Versions?!

Hi,

In effect, when I change the BC to patch it does not even run.... I dont know. Can you detail me your BC? So I can try to do the same?

thank!

Hello cristina,

my settings in the attachment. I hope it help you?

I forgot to tell you my Sovler. I use the buoyantBoussinesqSimpleFoam and the buoyantSimpleFoam.

Hi Micha,

¿your bottom is a wall? ¿like the ground?
Cristina

Hi,

no. I simulate a pipe an this surface is in my case the wall.