CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Programming & Development

Radiation heat transfer boundary condition

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 8, 2015, 09:05
Default Radiation heat transfer boundary condition
  #1
New Member
 
Nat Trask
Join Date: Mar 2009
Location: Providence, RI
Posts: 18
Rep Power: 15
natrask is on a distinguished road
Hi everyone,

I've been spending some time trying to incorporate the radiative heat transfer model into buoyant simple foam as a boundary condition (i.e. rather than using the conjugate heat transfer solver, I'm using a boundary condition accounting for heat transfer to an external fixed temperature with a prescribed heat transfer coefficient and coupling to radiation and turbulence models). This is more in line with standard HVAC setups. When I've looked through the forums I've only been able to find useful references for the conjugate heat transfer type cases.

My question is how to incorporate radiative heat transfer into a heat flux balance. As I understand it (and I would very much like to get this confirmed) there are no boundary conditions coupling the radiation model directly to the heat flux at the boundaries. As a starting point, I modified the Foam::externalWallHeatFluxTemperatureFvPatchScalar Field class to add the Qrad field into the balance:
i.e. (modulus minus signs so that heat flow into the domain is positive)
\sum q_i = 0
q_rad = Qrad
q_convection = -kappaEff \partial_n T
q_conduction = h_eff (T-T_inf)

So the issue is, as far as I can tell, this approach treats the radiation source explicitly (I treat the convection and conduction terms implicitly). I've had success with this for cases with moderate temperature differences (i.e. surfaces with ~100 K difference in surface temperatures), but for large temperature differences I can't get convergence. I'm using the view factor model with kEpsilon for the turbulence model. Has anyone attempted anything like this? It seems like if people have been working with these radiation models that this would be a standard setup to attempt. My concern is that if this is really an issue with explicit treatment of the source term this would require a fundamental change of the radiationmodel classes so that everything can be treated implicitly.

Thanks!
Nat
natrask is offline   Reply With Quote

Reply

Tags
boundary condition, externalwallheatflux, heat transfer, radiation, viewfactor

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
mass flow in is not equal to mass flow out saii CFX 12 March 19, 2018 05:21
Difficulty In Setting Boundary Conditions Moinul Haque CFX 4 November 25, 2014 17:30
Radiation interface hinca CFX 15 January 26, 2014 17:11
Question about heat transfer coefficient setting for CFX Anna Tian CFX 1 June 16, 2013 06:28
CFX fails to calculate a diffuser pipe flow shenying0710 CFX 7 March 26, 2013 04:13


All times are GMT -4. The time now is 00:01.