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-   -   To solve my own equation (http://www.cfd-online.com/Forums/openfoam-solving/59760-solve-my-own-equation.html)

lam March 23, 2007 07:06

Hi Rafal, As you said to me
 
Hi Rafal,

As you said to me it was possible, I create my own equation in Foam.
In icoFoam.C, I moved the Navier-Stokes equation for a another eqution easier:

nu*Laplacien(U)=Grad(p)

In th eicoFoam.C, I wrote this line below:
********************************************
fvVectorMatrix UEqn
(
fvm::laplacian(nu, U)
);
solve(UEqn == fvc::grad(p));
**********************************************

And I changed anything else, in any files
(of course, I made the ./Allmake)
But I had a wrong solution, when did:

icoFoam SFOAM_RUN/tutorials/icoFoam MyCavity
(MyCavity is a case that I created, diferent from the "cavity" case).

My solution is actually:

************************************************
Time = 0.01

Mean and max Courant Numbers = nan nan
ICCG: Solving for Ux: solution singularity
ICCG: Solving for Uy: solution singularity
ICCG: Solving for Uz: solution singularity
ICCG: Solving for p: solution singularity
time step continuity errors : sum local = nan, global = nan, cumulative = nan
ICCG: Solving for p: solution singularity
time step continuity errors : sum local = nan, global = nan, cumulative = nan
ExecutionTime = 0.75 s ClockTime = 1 s
************************************************

I know there is somethin wrong with the timeStep here. But I do not know what and where I have to cahnge things to solve my problem!

Can you, or someboby else, give me some advice?

Thanks in advance,

Lam

rafal March 23, 2007 07:36

Hi Lam, there can be many c
 
Hi Lam,

there can be many causes of solution singularity.
Several thing that I can see here.
- you removed time derivative and you try to solve
something in time(maybe start with different solver for steady state ie simpleFoam)

- the equation now is diagonally equal
(since diffusion term produce diagonally equal
matrix; grad(p) is source term) and matrix
has to be diagonally dominant to solve it.


these are my quick ideas (i can be wrong)
rafal

lam March 23, 2007 08:30

Thamks Rafal to reply me, I
 
Thamks Rafal to reply me,

I'm thinkin about your ideas.

Regards,

Lam

lam March 28, 2007 06:04

Hi world! I did a big mista
 
Hi world!

I did a big mistake, I delete by accident my doc/Doxygen/html!!
How can I get it again???

Thanks in advance,

Lam

rafal March 28, 2007 06:21

you can untar OF project in OT
 
you can untar OF project in OTHER directory
than ~/OpenFOAM. and than move it to right place:
i.e:
$ mkdir other
$ cd other
$ tar -xzf /path/to/OpenFoam-1.3.General.tgz #not sure of name here
$ mv other/OpenFOAM-1.3/doc/Doxygen ~/OpenFOAM/OpenFOAM-1.3/doc
$ cd ..
$ rm -rf other
this should work
rafal

lam March 28, 2007 09:35

Oki, Rafal! You're right!
 
Oki, Rafal!

You're right!
Thanks a lot!

Lam

lam March 29, 2007 07:30

Hi world, I'm wondering mys
 
Hi world,

I'm wondering myself again about simpleFoam.C

I noticed that I could put the turbulence in "off":
but what kind of equation will I solve as result?

Somebody can help me?

Thanks in advance,
Lam

lam March 30, 2007 03:37

HEY, everyone! Nobody can g
 
HEY, everyone!

Nobody can give me some advice?

Cheers,

LAm


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