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

Convective boundary condition

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 22, 2008, 10:34
Default Dear OF community, I'm tryi
  #1
New Member
 
Andrea M.A. Barbera
Join Date: Mar 2009
Location: Turin, Italy
Posts: 7
Rep Power: 17
andrea_barbera is on a distinguished road
Dear OF community,

I'm trying to implement a convective boundary condition in OF. Essentially this condition should be applied in a solid domain and should guarantee the coherence of thermal fluxes at the interface between the solid and a hypotetic fluid. This condition should respect the known equation:

-k*dT/dn = HTC*(T-T_fluid)

Where k, HTC and T_fluid are parameters of the boundary condition (I think to have succesfully loaded them in my BC), and T and dT/dn are respectively the gradient and the value that I must impose.

From which BC should I start to obtain my BC? I tried to start from BC derived from fixedValue, fixedGradient and mixed, but I do not know how to impose a linear combination of two fields like T and dT/dn and where impose it.

I have tried some tricks:

---- Starting from fixedValue-derived BCs I try to discretize the gradient as

(T_to_set - this->patchInternalField())
*this->patch().deltaCoeffs())

getting an equation in "T_to_set", the value that I try to set as BC.


---- Starting from fixedGradient-based BCs I try to discretize T as

(gradient_to_set + *this->patch().deltaCoeffs()) + this->patchInternalField()

getting an equation in "gradient_to_set", the value that I try to set as BC.

Unfortunaley these triks had no results and I get no result, also for some problem related to type mismatch during compiling. I do not know how to start implement this BC starting from mixed-BC or if the trikc that I have followed are reasonable

Can you help me?

Best regards

Andrea
andrea_barbera is offline   Reply With Quote

Old   September 22, 2008, 11:40
Default Hi Andrea, I think you can
  #2
Super Moderator
 
Takuya OSHIMA
Join Date: Mar 2009
Location: Niigata City, Japan
Posts: 518
Blog Entries: 1
Rep Power: 20
7islands is on a distinguished road
Hi Andrea,

I think you can have a look at either
1. the mixed-derived advective b.c. in OF 1.5 or
2. [Advertisement] the fixedGradient-derived convectiveOutlet b.c. I posted here on Sep. 05, 2007.

1. is much more sophiscated but may require a bit of patience to read.

Takuya
7islands is offline   Reply With Quote

Old   September 23, 2008, 04:16
Default Hi Takuya, Thanks for your
  #3
New Member
 
Andrea M.A. Barbera
Join Date: Mar 2009
Location: Turin, Italy
Posts: 7
Rep Power: 17
andrea_barbera is on a distinguished road
Hi Takuya,

Thanks for your advise. I will check these boundary conditions and start from them!

Andrea
andrea_barbera is offline   Reply With Quote

Old   September 24, 2009, 07:45
Default
  #4
Member
 
Jitao Liu
Join Date: Mar 2009
Location: Jinan , China
Posts: 64
Rep Power: 17
awacs is on a distinguished road
Hi Andrea,

I am interested in this convective boundary condition too. Have you finished it?

I am study the heating process of a solid, which has several heating channels for hot gas or hot oil flowing through. So the boundary condition at the channel wall shuold belongs to the third-class, just as you described above:
-k*dT/dn = HTC*(T-T_fluid)

Please give me some suggestions. Thanks in advance.

Regards,
Jitao
awacs is offline   Reply With Quote

Old   March 4, 2010, 05:36
Default
  #5
bhh
Member
 
Bjorn H. Hjertager
Join Date: Mar 2009
Posts: 72
Rep Power: 17
bhh is on a distinguished road
Hi Andrea,

I am also interested in implementing the mixed heat transfer BC. Did you manage to make it?

rgds
Bjorn
bhh is offline   Reply With Quote

Reply


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
convective boundary condition Mani CFX 8 March 21, 2017 10:59
convective boundary condition for outflow BC Pang Shengyong Main CFD Forum 1 August 24, 2007 18:21
Convective Boundary Condition garni FLUENT 0 September 25, 2005 14:00
Convective boundary condition STN Main CFD Forum 5 May 29, 2002 09:47
convective boundary condition frederic felten Main CFD Forum 1 April 25, 2001 02:20


All times are GMT -4. The time now is 23:54.