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Initialization with potentialFoam

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Old   October 1, 2012, 04:05
Default Initialization with potentialFoam
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Sune Niemann
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I upgraded from 1.6.x to 2.1.0, and I noticed that it is now possible to include initialization of fields with potentialFoam, quite simply by including the potentialFlow keyword to the fvSolution dictionary, which is great. Using potentialFoam this way however, limits potentialFoam to use the same solvers and settings as used with for example simpleFoam.

Before I upgraded I used two fvSolution dicts, i.e fvSolution.potentialFoam and fvSolution.simpleFoam and then created a symbolic link to the fvSolution file before running potentialFoam or simpleFoam respectively. Does anyone know of a simpler way of setting solvers and their settings for simpleFoam and potentialFoam individually, using only one fvSolution file?

Thanks in advance

Sune
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Old   October 1, 2012, 06:22
Default How to run potentialFoam and simpleFoam together .
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sandip
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I want to run the potentialFoam with few iterations and then run the simpleFoam using the same controlDict and fvSolution files , what changes are needed for openFoam2.1.0
Is it necessary to specify the residual controls in fvSolution file for simpleFoam.
Idea is to use results of potentialFoam for simpleFoam as intial conditions.

with regards.
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Old   October 1, 2012, 07:29
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Sune Niemann
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Quote:
Originally Posted by vmsandip2011 View Post
I want to run the potentialFoam with few iterations and then run the simpleFoam using the same controlDict and fvSolution files , what changes are needed for openFoam2.1.0
Is it necessary to specify the residual controls in fvSolution file for simpleFoam.
Idea is to use results of potentialFoam for simpleFoam as intial conditions.

with regards.
You can easily use potentialFoam to initialize your fields with, just include the keyword potentialFlow at the end of your fvSolution file as shown in the code below.

Code:
solvers
{
    p
    {
        solver          PCG;
        preconditioner  DIC;
        tolerance       1e-12;
        relTol          0.0001;
    }
 
    // And all the rest of your solvers 
}
 
SIMPLE
{
    nNonOrthogonalCorrectors  1;
    pRefPoint                 (0 0 0.5);
    pRefValue                 0;
 
    residualControl
    {
         p                       1e-9;
         U                       1e-9;
         //etc.
    }
}
 
potentialFlow
{
    nNonOrthogonalCorrectors 10;
}
Using the above code, will use 10 non-orthogonal corrector steps using whatever maxIter you have set for your solvers, giving nicely initialized fields.

So far as I know you can't use this same method to control the solution algorithms individually, which was what my question was about.
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Old   October 1, 2012, 07:57
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sandip
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Hi
Thanks for the reply .
I tried using fvSolution file as changes you have suggested , but I am getting following error
when I am running potentialFoam
.....
Create time
Create mesh for time = 0
Reading field p
Reading field U

Calculating potential flow
GAMG: Solving for p, Initial residual = 1.#QNAN, Final residual = 1.#QNAN, No Iterations 1000

--> FOAM FATAL ERROR:
Unknown functionEntry 'QNAN' in "IStringStream.sourceFile" near line 3
Valid functionEntries are :

4
(
codeStream
include
calc
includeIfPresent
)

From function functionEntry::execute(const word&, const dictionary&, primitiveEntry&, Istream&)
in file db/dictionary/functionEntries/functionEntry/functionEntry.C at line 129.

FOAM exiting

can you throw some light on what could be the wrong .

with regards
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Old   October 1, 2012, 09:45
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Sune Niemann
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I am not entirely sure what happened to your simulation, and probably some more experienced OF user could give you a better answer, but what I notice is:
Quote:
GAMG: Solving for p, Initial residual = 1.#QNAN, Final residual = 1.#QNAN, No Iterations 1000
- your initial residual at the point where the simulation crashes is QNAN, which I guess is a quite NAN, so you probably have some divergence or division by zero stuff going on.
- you have set the number of iterations to 1000 for GAMG under p in solvers. It will probably not solve your problem, but try and set maxIter to 10, to see if the error occurs instantaneously.

Also posting your entire fvSolution file would help.
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