Matrix in OpenFoam
 

Hello Mr. Bruno

According to the reference that it's address link is below, in page 53;
http://www.diva-portal.org/smash/get...T01.pdf‎
I can,t undrestand that what is the placeholder matrix in openFoam? and how get this equations:

u(0)=[2,0] u(1)=[3,1] l(0)=[0,2] l(1)=[1,3]

UpperAddr=(2,3) LowerAddr=(0,1)

If it is possible for you, please explain a little about this concept.
Best regards,
Hassan

Hi Hassan,

Sorry, but this is beyond my experience level.
My suggestion is that you'll have to search for more information on this topic, possibly among the reference thesis made around OpenFOAM and the OpenFOAM Programmers Guide: http://foam.sourceforge.net/docs/Gui...mmersGuide.pdf

Good luck! Best regards,
Bruno

thank you Mr. Bruno:)

Ueqn
 

Hi,
In the icoFoam solver, where is the top level of Ueqn where Navier-stoke equation carries out?

best regards,
Hassan

Hi Hassan,

The best I can do on this question is to point you to this wiki page: http://openfoamwiki.net/index.php/IcoFoam - it basically explains how the icoFoam solver works.

Best regards,
Bruno

Hi friends,
I can't understand the PCG linear solver how work in the icoFoam solver? In other words, which part of the icoFoam.C related to the PCG linear solver and use it? please show me.

Regards,
Hassan

Hi Hassan,

The PCG solver is not available directly to icoFoam. It's used very deep into the solve() methods and equation solving algorithms.

Some more reading material:

• http://openfoamwiki.net/index.php/OpenFOAM_guide
• http://powerlab.fsb.hr/ped/kturbo/Op...jeJasakPhD.pdf
• http://www.foamcfd.org/resources/theses.html

Best regards,
Bruno

Thanks.
Regards,
Hassan.

Dear Foamers,
How can I extract the linear system (AX=B) from the cavity case in tutorials using OpenFOAM?


Regards,
Hassan

extract the linear system
 

Hi dear Bruno,
Could I use the PCG linear solver for my linear system (Ax=b) separately? In the other words, I want to send two input files A and b, then get the x from this solver? yes or no please?

regards,
Hassan

Hi Hassan,

I'm sorry to say that I don't know the answer. In theory, it should be possible.
AFAIK, do keep in mind that PCG will not be able to give you an exact solution. At most, it's able to give you a partial/possible near solution, but not an exact one: http://www.cfd-online.com/Wiki/Conju...adient_methods

If I had to start investigating into this, I would have a look into the source code experiments that try to use one or more GPUs to help solve simulations faster, such as:

• http://www.symscape.com/gpu-1-0-openfoam - this one refers to the official OpenFOAM versions
• http://code.google.com/p/cufflink-library/ - this one refers to the 1.6-ext Extend variant.

I say this because these libraries will sort-of hack directly into the LDU matrix management/solving system.


Best regards,
Bruno

Hi Hassan,

I am also working on the same problem of solving sparse linear matrix (AX=B) using PCG solver.
Did you find any solution ? Any useful inputs from your side apart from what is available here?

Thanks,
Meher.

Hi Meher,
thanks for your attention, but no.