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trouble with the boundary conditions(natural convection) |
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September 29, 2012, 06:01 |
trouble with the boundary conditions(natural convection)
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#1 |
Member
ankur
Join Date: May 2012
Location: India
Posts: 50
Rep Power: 13 |
Hey guys,
I am using Openfoam 2.0, I am simulating a cylinder with some tubes inside it carrying steam. My cylinder is open from bottom and top so that air enters from bottom and goes out from the top by getting heated up by the steam. I am using buoyantBoussinesqPimpleFoam solver. I am pasting my boundary conditions here, 0/U: internalField uniform (0 0 0); boundaryField { inlet { type zeroGradient; } pipe { type fixedValue; value uniform (0 0 0); } outlet { type zeroGradient; } wall { type fixedValue; value uniform (0 0 0); } symmetry { type symmetryPlane; } } 0/p_rgh: internalField uniform 0; boundaryField { inlet { type zeroGradient; } pipe { type buoyantPressure; rho rhok; value uniform 0; } outlet { type buoyantPressure; rho rhok; value uniform 0; } wall { type buoyantPressure; rho rhok; value uniform 0; } symmetry { type symmetryPlane; } } 0/p: boundaryField { inlet { type calculated; value $internalField; } pipe { type calculated; value $internalField; } outlet { type calculated; value $internalField; } wall { type calculated; value $internalField; } symmetry { type symmetryPlane; } } 0/T: internalField uniform 300; boundaryField { inlet { type zeroGradient; } pipe { type fixedValue; value uniform 413; } outlet { type zeroGradient; } wall { type zeroGradient; } symmetry { type symmetryPlane; } } all other parameters are zeroGradient at inlet and outlet, and fixed value at the walls. I am getting a good flow patters and velocity vectors are in right direction but I am getting a problem with the temperature and it is going below 298 K for air, which is non physical for this case. Can you please help me in choosing the right boundary conditions. I am attaching some snapshots with this thread. Thank You |
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September 30, 2012, 14:04 |
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#2 |
Senior Member
Tian
Join Date: Mar 2009
Location: Berlin, germany
Posts: 119
Rep Power: 17 |
Hi,
I think you should set the temperatur field for the inlet condition also. I test it with a similar case and it was working... Bye Thomas |
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October 1, 2012, 03:47 |
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#3 |
Member
ankur
Join Date: May 2012
Location: India
Posts: 50
Rep Power: 13 |
Hey thanks for your reply,
can you please tell me what other boundary conditions you used for the pressure velocity, k , epsilon etc..I cant see your attachment properly. Ankur |
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October 1, 2012, 07:04 |
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#4 |
Senior Member
Tian
Join Date: Mar 2009
Location: Berlin, germany
Posts: 119
Rep Power: 17 |
Hi Ankur,
i used the HVAC Tool to build a similar case quickly (file ending *.hvac). I take your BC. I only changed the inlet BC as fixedValue for temperature. Bye Thomas |
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October 1, 2012, 07:28 |
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#5 |
Member
ankur
Join Date: May 2012
Location: India
Posts: 50
Rep Power: 13 |
hey thanks alot again..
I used pressureInletOutletVelocity also along with the fixed temperature bc..is it right to use it here? Now my temperature is coming in the right range.. Thanks Ankur |
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October 2, 2012, 12:46 |
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#6 |
New Member
Eric
Join Date: Aug 2010
Posts: 14
Rep Power: 15 |
Hello Ankur, You might find this thread helpful:
http://www.cfd-online.com/Forums/ope...condition.html |
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October 3, 2012, 03:50 |
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#7 |
Member
ankur
Join Date: May 2012
Location: India
Posts: 50
Rep Power: 13 |
hey Thanks Eric, I will run a test case with this BC also, I have not given total pressure ever as my BC. I am running with atmospheric on inlet and zeroGradient on outlet. For k and epsilon i have given zeroGradient on inlet and outlet.
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