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-   -   How to define Boundary Conditions in heat Transfer ?? (http://www.cfd-online.com/Forums/openfoam/90641-how-define-boundary-conditions-heat-transfer.html)

almir July 16, 2011 16:07

How to define Boundary Conditions in heat Transfer ??
 
hi,
i want to make a research on natural convection, for that i have to use OpenFoam.
As solver my plan is to use buoyantSimpleFoam or buoyantSimpleRadiationFoam (if you know a better solver please tell me ;-) )
My geometry is a cylinder (1m long, diameter 5cm) which has a temperature of 70°C, the room in which the the cylinder is have a temperature of 20 °C. I have the geometry edited in BlockMeshDict as 2-Dmodel, i also have the model in a 3-D model meshed by Netgen.
The geometry you can see in the picture.
I want to get by OpenFoam results for the velocity, i have measured in a test rig that the velocity is u = 0,05m/s to 0,25 m/s.

My problem now is how i can define the boundary conditions.

i donīt know which value alphat, epsilon, k, mut and omega from the buoyantSimpleFoam-tutorial should have?

or which value alphat, epsilon, G, k, and mut from the buoyantSimpleRadiationFoam-tutorial should have?

if i use the tutorials, and edit the temperature to 20°C and 70°C and the pressure to 1bar, i always get a Error message.

Can somebody help me?
thanks and greets
almir

http://s7.directupload.net/images/110716/tgs6oyqp.jpg

nimasam July 18, 2011 03:33

hi
1) if u access to fluent documentation you can find how to calculate first approximation for k-epsilon
or here :
http://www.cfd-online.com/Forums/ope...lon-model.html

2) as i remember mut and alphat can be set calculated

3 ) buoyantSimpleRadiationFoam-tutorial :
http://www.google.com/url?sa=t&sourc...zGzXIw&cad=rja

jignesh_thaker2007 September 27, 2011 03:10

hiiiiii
 
hi,
i want to make a project on openFoam. i solved cavity problem for isothermal flow now i want to go for nonisothermal problem for cavity laminar flow it means natural convection flow.so as solver what r the modification require in icoFoam solver.

My problem now is how i can define the boundary conditions.

i donīt know which value alphat, epsilon, k, mut and omega from the buoyantSimpleFoam-tutorial should have? so i m so confused

Can somebody help me?
thanks and greets
jignesh

Bernhard September 27, 2011 03:20

Please post your questions not in multiple topics, that is confusing:
http://www.cfd-online.com/Forums/ope...onvection.html


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