CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

Which application should I use to solve this equation

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 20, 2011, 23:58
Default Which application should I use to solve this equation
  #1
New Member
 
qi bin
Join Date: Jan 2011
Posts: 5
Rep Power: 6
qibintj is on a distinguished road
Hello Foamers,
I am a beginner, which application should I use to solve these equation

In region 1
∇∙[(1-s)^1.5 ∇c]=0
∇∙[s^3 (-4.24s+〖3s〗^2)∇s]=0

In region 2
∇∙[(1-s)^1.5 ∇c]=1-s
∇∙[s^3 (-4.24s+〖3s〗^2)∇s]=1-s

anyhelp will be thankful.
qibintj is offline   Reply With Quote

Old   January 21, 2011, 03:29
Default
  #2
Senior Member
 
Bernhard
Join Date: Sep 2009
Location: Delft
Posts: 790
Rep Power: 12
Bernhard is on a distinguished road
I suggest to write your own application, that is what you can do with OpenFOAM relatively easily. No guarantees for convergent solutions however. Especially since you equations are not very linear in s Good luck!
Bernhard is offline   Reply With Quote

Old   January 21, 2011, 05:00
Default
  #3
New Member
 
qi bin
Join Date: Jan 2011
Posts: 5
Rep Power: 6
qibintj is on a distinguished road
Thanks.
Are there similar standard applications I can modify to solve it?
qibintj is offline   Reply With Quote

Old   January 21, 2011, 05:22
Default
  #4
Senior Member
 
Bernhard
Join Date: Sep 2009
Location: Delft
Posts: 790
Rep Power: 12
Bernhard is on a distinguished road
You can have a look in the basic solvers to start with.
Bernhard is offline   Reply With Quote

Old   January 21, 2011, 07:46
Default
  #5
Cyp
Senior Member
 
Cyprien
Join Date: Feb 2010
Location: Stanford University
Posts: 229
Rep Power: 9
Cyp is on a distinguished road
Hi!

I think you can start from laplacianFoam and define a source term that depends on the region you consider. You can develop something like that :

Code:
volScalarField source = alpha * (1-S) + (scalar(1)-alpha);
volScalarField Sc = pow((1-S),1.5);
volScalarField Ss = pow(S,3)*(-4.24*S + pow(3*S,2))

solve ( fvm::laplacian(Sc,c) == source );
solve ( fvm::laplacian(Ss,S) == source );
where alpha is a volScalarField defined by
- 0 within Region 1
- 1 within Region 2

I advise you to use the setFields utility to set up alpha.
Be careful to the units.

Best regards,
Cyp

Last edited by Cyp; January 21, 2011 at 10:16.
Cyp is offline   Reply With Quote

Old   January 24, 2011, 02:01
Default
  #6
New Member
 
qi bin
Join Date: Jan 2011
Posts: 5
Rep Power: 6
qibintj is on a distinguished road
Thanks a lot
Another question, how can I deal with the interface boundary condition between region1 and region2. Suppose c(region1)=c(region2).
qibintj is offline   Reply With Quote

Old   January 24, 2011, 05:06
Default
  #7
Cyp
Senior Member
 
Cyprien
Join Date: Feb 2010
Location: Stanford University
Posts: 229
Rep Power: 9
Cyp is on a distinguished road
I guess that if you defined your 2 regions by an indicator function such as "alpha", the continuity is automatically garanteed.

Regards,
Cyp
Cyp is offline   Reply With Quote

Old   January 24, 2011, 16:52
Default
  #8
Senior Member
 
Ben K
Join Date: Feb 2010
Location: Ottawa, Canada
Posts: 140
Rep Power: 10
benk is on a distinguished road
Quote:
Originally Posted by qibintj View Post
Another question, how can I deal with the interface boundary condition between region1 and region2. Suppose c(region1)=c(region2).
You can use conjugateHeatFoam (in the dev versions) or chtMultiRegionFoam for this. These solvers will ensure a continuous flux between the regions as well as c(region1)=c(region2).
benk is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Q: how to solve linear equation dut_thinker FLOW-3D 2 September 2, 2010 22:17
Poisson equation combined with transport equation Se-Hee CFX 0 December 27, 2007 02:00
Solve Poissons Equation Anil CFX 8 September 25, 2007 12:57
How to solve a scalar equation with Fluent Tomik FLUENT 1 January 8, 2006 07:18
how to solve an equation at an interface sreenivas CFX 0 May 14, 2004 09:35


All times are GMT -4. The time now is 20:56.