# How to define Boundary Conditions in heat Transfer ??

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 July 16, 2011, 15:07 How to define Boundary Conditions in heat Transfer ?? #1 New Member   Join Date: May 2011 Location: Germany/Bosnia Posts: 9 Rep Power: 8 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

 July 18, 2011, 02:33 #2 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,240 Blog Entries: 1 Rep Power: 18 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

 September 27, 2011, 02:10 hiiiiii #3 Member   Jignesh Join Date: Aug 2011 Location: India Posts: 68 Rep Power: 8 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

 September 27, 2011, 02:20 #4 Senior Member   Bernhard Join Date: Sep 2009 Location: Delft Posts: 790 Rep Power: 15 Please post your questions not in multiple topics, that is confusing: http://www.cfd-online.com/Forums/ope...onvection.html

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