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Old   March 15, 2011, 13:07
Default Full pipe 3D using icoFoam
  #1
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Petar Zivkovic
Join Date: Feb 2011
Posts: 6
Rep Power: 6
cyberbrain is on a distinguished road
Hi foamers! hope someone has solution for my problem because i don't know what is going on with my model!

First of all i have to mention that i modeled 3D rectangular pipe,unsteady laminar flow, and simulation went fine after some tweaking ... i got stable solution in this case but as soon as i change geometry (with same p,U,boundery fields,fvSolution,fvSchemas...etc) i can't tweak model to convergent.

Definition of the problem:


This is how I modeled it:


My input files:
-blockMeshDict:
Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.1;

vertices        
(
	(-0.15 0 -0.15)
	(0.15 0 -0.15)
	(0.15 0 0.15)
	(-0.15 0 0.15)
	(-0.35355 0 -0.35355)
	(0.35355 0 -0.35355)
	(0.35355 0 0.35355)
	(-0.35355 0 0.35355)

	(-0.15 10 -0.15)
	(0.15 10 -0.15)
	(0.15 10 0.15)
	(-0.15 10 0.15)
	(-0.35355 10 -0.35355)
	(0.35355 10 -0.35355)
	(0.35355 10 0.35355)
	(-0.35355 10 0.35355) );

blocks          
(
    	hex (0 3 2 1 8 11 10 9) (10 10 50) simpleGrading (1 1 1)
	hex (0 1 5 4 8 9 13 12) (10 10 50) simpleGrading (1 1 1)
	hex (1 2 6 5 9 10 14 13) (10 10 50) simpleGrading (1 1 1)
	hex (2 3 7 6 10 11 15 14) (10 10 50) simpleGrading (1 1 1)
	hex (3 0 4 7 11 8 12 15) (10 10 50) simpleGrading (1 1 1)
);

edges           
(
	arc 4 5 (0 0 -0.5)
	arc 5 6 (0.5 0 0)
	arc 6 7 (0 0 0.5)
	arc 7 4 (-0.5 0 0)
	arc 12 13 (0 10 -0.5)
	arc 13 14 (0.5 10 0)
	arc 14 15 (0 10 0.5)
	arc 15 12 (-0.5 10 0)
);

patches         
(
    patch
	inlet
    (
        (0 3 2 1)
	(0 1 5 4)
	(1 2 6 5)
	(2 3 7 6)
	(3 0 4 7)
    )
    patch 
	outlet
    (
	(8 9 10 11)
	(8 12 13 9)
	(9 13 14 10)
	(10 14 15 11)
	(11 15 12 8)	
    )
    wall
	walls
    (
	(4 5 13 12)
	(5 6 14 13)
	(6 7 15 14)
	(7 4 12 15)
    )
);

mergePatchPairs 
(
);

// ************************************************************************* //
-controlDict:
Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application     icoFoam;

startFrom       startTime;

startTime       0;	

stopAt          endTime;	

endTime         30;

deltaT          1;

writeControl    timeStep;

writeInterval   1;	

purgeWrite      0;	

writeFormat     ascii;		

writePrecision  6;		

writeCompression uncompressed;

timeFormat      general;

timePrecision   6;	

runTimeModifiable yes;	


// ************************************************************************* //
-fvSchemes:
Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
        default         Euler;
//	default		steadyState;
}

gradSchemes
{
    default         Gauss linear;
    grad(p)         Gauss linear;
}

divSchemes
{
    default         none;
    div(phi,U)      Gauss linear;
}

laplacianSchemes
{
    default         none;
    laplacian(nu,U) Gauss linear corrected;
    laplacian((1|A(U)),p) Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
    interpolate(HbyA) linear;
}

snGradSchemes
{
    default         corrected;
}

fluxRequired
{
    default         no;
    p               ;
}


// ************************************************************************* //
-fvSolution:
Code:
solvers
{
    p
    {
	solver		PCG;
	preconditioner	DIC;
	tolerance	1e-06;
	reTol		0;	
    }	

    U
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-05;
        relTol          0;
    }
}

PISO
{
    nCorrectors     2;
    nNonOrthogonalCorrectors 0;
    pRefCell        0;
    pRefValue       0;
}

// ************************************************************************* //
- 0/p
Code:
dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    inlet      
    {
        type            zeroGradient;
    }

    outlet     
    {
        type            fixedValue;
	value		uniform 0;
    }

    walls    
    {
        type            zeroGradient;
    }
}
-0/U
Code:
dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    inlet      
    {
        type            fixedValue;
        value           uniform (0 1 0);
    }

    outlet      
    {
        type           zeroGradient;
    }

    walls    
    {
        type            fixedValue;
	value 		uniform (0 0 0);
    }
}
So as u can see i need velocity on inlet (0 1 0) and presure an outlet (0)...
really can't find problem...maybe icoFoam is not solver that i should use for this problem...any sugestion would be great!

finally these errors and results i get on calculation:

Code:
Create time

Create mesh for time = 0

Reading transportProperties

Reading field p

Reading field U

Reading/calculating face flux field phi


Starting time loop

Time = 1

Courant Number mean: 0 max: 100
DILUPBiCG:  Solving for Ux, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG:  Solving for Uy, Initial residual = 1, Final residual = 7.24921e-06, No Iterations 35
DILUPBiCG:  Solving for Uz, Initial residual = 0, Final residual = 0, No Iterations 0
DICPCG:  Solving for p, Initial residual = 1, Final residual = 9.26667e-07, No Iterations 151
time step continuity errors : sum local = 9.26667e-07, global = 8.46286e-09, cumulative = 8.46286e-09
DICPCG:  Solving for p, Initial residual = 0.00918897, Final residual = 9.76998e-07, No Iterations 136
time step continuity errors : sum local = 9.97464e-05, global = -9.91256e-07, cumulative = -9.82793e-07
ExecutionTime = 1.41 s  ClockTime = 2 s

Time = 2

Courant Number mean: 4.98906 max: 143.985
DILUPBiCG:  Solving for Ux, Initial residual = 0.751531, Final residual = 9.97711e-06, No Iterations 28
DILUPBiCG:  Solving for Uy, Initial residual = 0.313552, Final residual = 8.39474e-06, No Iterations 29
DILUPBiCG:  Solving for Uz, Initial residual = 0.75153, Final residual = 7.57783e-06, No Iterations 29
DICPCG:  Solving for p, Initial residual = 0.49221, Final residual = 8.38074e-07, No Iterations 147
time step continuity errors : sum local = 1.2671e-05, global = -8.75128e-09, cumulative = -9.91545e-07
DICPCG:  Solving for p, Initial residual = 0.0117698, Final residual = 7.11563e-07, No Iterations 137
time step continuity errors : sum local = 0.000408209, global = 2.92362e-06, cumulative = 1.93208e-06
ExecutionTime = 2.49 s  ClockTime = 3 s

Time = 3

Courant Number mean: 26.4226 max: 916.486
DILUPBiCG:  Solving for Ux, Initial residual = 0.809749, Final residual = 9.30861e-06, No Iterations 31
DILUPBiCG:  Solving for Uy, Initial residual = 0.389871, Final residual = 7.63744e-06, No Iterations 40
DILUPBiCG:  Solving for Uz, Initial residual = 0.809748, Final residual = 9.34365e-06, No Iterations 36
DICPCG:  Solving for p, Initial residual = 0.604599, Final residual = 9.48499e-07, No Iterations 147
time step continuity errors : sum local = 8.65678e-05, global = 1.26445e-07, cumulative = 2.05852e-06
DICPCG:  Solving for p, Initial residual = 0.0148976, Final residual = 7.70586e-07, No Iterations 137
time step continuity errors : sum local = 0.00252944, global = -1.84451e-05, cumulative = -1.63866e-05
ExecutionTime = 3.67 s  ClockTime = 4 s

Time = 4

Courant Number mean: 147.201 max: 4510.08
DILUPBiCG:  Solving for Ux, Initial residual = 0.77792, Final residual = 9.67807e-06, No Iterations 73
DILUPBiCG:  Solving for Uy, Initial residual = 0.489883, Final residual = 5.18925e-06, No Iterations 73
DILUPBiCG:  Solving for Uz, Initial residual = 0.77792, Final residual = 6.03916e-06, No Iterations 73
DICPCG:  Solving for p, Initial residual = 0.694876, Final residual = 8.19978e-07, No Iterations 148
time step continuity errors : sum local = 0.000558808, global = 2.33549e-06, cumulative = -1.40511e-05
DICPCG:  Solving for p, Initial residual = 0.0226691, Final residual = 6.59866e-07, No Iterations 139
time step continuity errors : sum local = 0.0122011, global = 9.60505e-05, cumulative = 8.19994e-05
ExecutionTime = 5.32 s  ClockTime = 5 s
.
.
.
Time = 14

Courant Number mean: 2.95062e+86 max: 2.42912e+89
DILUPBiCG:  Solving for Ux, Initial residual = 0.998523, Final residual = 1.01741e+07, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.994646, Final residual = 2.2903, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999568, Final residual = 69.2939, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 35.9498, No Iterations 1001
time step continuity errors : sum local = 1.53483e+98, global = -3.01763e+92, cumulative = -3.01763e+92
DICPCG:  Solving for p, Initial residual = 0.950592, Final residual = 54.6822, No Iterations 1001
time step continuity errors : sum local = 2.09996e+101, global = -1.03985e+97, cumulative = -1.03988e+97
ExecutionTime = 142.67 s  ClockTime = 143 s

Time = 15

Courant Number mean: 1.99707e+101 max: 2.02545e+104
#0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#1  Foam::sigFpe::sigFpeHandler(int) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#2  Uninterpreted: 
#3  Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#4  
 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam"
#5  
 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam"
#6  __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#7  
 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam"
Floating point exception
And finaly resultat is crap! (pressure field seems fine on first time step...after that goes crazy)...





Thanks in advance...my CFD knowledge was based on basics of Finite Elements method...so Finite Volumes is something new for me...so sorry for some stupid mistakes if i made using OpenFOAM!

regards!
Petar Zivkovic
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Old   March 15, 2011, 13:21
Default
  #2
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Martin
Join Date: Oct 2009
Location: Aachen, Germany
Posts: 252
Rep Power: 11
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Hi Petar,

reduce deltaT in system/controlDict to a much lower value, say 0.001, and try again.

Martin
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Old   March 15, 2011, 14:16
Default
  #3
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Petar Zivkovic
Join Date: Feb 2011
Posts: 6
Rep Power: 6
cyberbrain is on a distinguished road
Hi Matin,
Thanx for quick replay... but same problem occurred:
Code:
Time = 0.015

Courant Number mean: 15.6518 max: 277.137
DILUPBiCG:  Solving for Ux, Initial residual = 0.745384, Final residual = 8.16797e-06, No Iterations 53
DILUPBiCG:  Solving for Uy, Initial residual = 0.78606, Final residual = 8.31362e-06, No Iterations 50
DILUPBiCG:  Solving for Uz, Initial residual = 0.745302, Final residual = 5.90854e-06, No Iterations 50
DICPCG:  Solving for p, Initial residual = 0.904914, Final residual = 8.3528e-07, No Iterations 227
time step continuity errors : sum local = 6.3841e-05, global = -1.01036e-07, cumulative = -3.16388e-07
DICPCG:  Solving for p, Initial residual = 0.713999, Final residual = 9.34143e-07, No Iterations 221
time step continuity errors : sum local = 0.000113492, global = -2.62634e-08, cumulative = -3.42651e-07
ExecutionTime = 17.02 s  ClockTime = 17 s

Time = 0.016

Courant Number mean: 69.3057 max: 50974.2
DILUPBiCG:  Solving for Ux, Initial residual = 0.999403, Final residual = 0.0429228, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.998282, Final residual = 0.426477, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999378, Final residual = 0.0676183, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 0.979382, Final residual = 8.03998e-07, No Iterations 762
time step continuity errors : sum local = 0.00285593, global = 2.08686e-06, cumulative = 1.7442e-06
DICPCG:  Solving for p, Initial residual = 0.993121, Final residual = 5.441e-07, No Iterations 869
time step continuity errors : sum local = 0.368197, global = 0.00145017, cumulative = 0.00145192
ExecutionTime = 33.06 s  ClockTime = 33 s

Time = 0.017

Courant Number mean: 2.25409e+06 max: 1.33605e+10
DILUPBiCG:  Solving for Ux, Initial residual = 1, Final residual = 1.26774, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 1, Final residual = 6.16202, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 1, Final residual = 14331.8, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 2.86475, No Iterations 1001
time step continuity errors : sum local = 5.61093e+18, global = 3.57396e+12, cumulative = 3.57396e+12
DICPCG:  Solving for p, Initial residual = 0.998461, Final residual = 6.10091, No Iterations 1001
time step continuity errors : sum local = 2.83525e+22, global = -7.04584e+16, cumulative = -7.04548e+16
ExecutionTime = 49.9 s  ClockTime = 51 s

Time = 0.018

Courant Number mean: 2.82832e+22 max: 3.0603e+25
DILUPBiCG:  Solving for Ux, Initial residual = 0.998746, Final residual = 34.4554, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.997935, Final residual = 1.09843, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999978, Final residual = 5.21295, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 994.164, No Iterations 1001
time step continuity errors : sum local = 9.01643e+34, global = -1.1094e+25, cumulative = -1.1094e+25
DICPCG:  Solving for p, Initial residual = 0.854007, Final residual = 2.57049, No Iterations 1001
time step continuity errors : sum local = 1.51861e+36, global = -5.055e+28, cumulative = -5.05611e+28
ExecutionTime = 68.06 s  ClockTime = 70 s

Time = 0.019

Courant Number mean: 1.47917e+36 max: 6.46245e+39
DILUPBiCG:  Solving for Ux, Initial residual = 0.99976, Final residual = 1.32634, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.999817, Final residual = 2.27595, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999836, Final residual = 1.46444, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 14.1995, No Iterations 1001
time step continuity errors : sum local = 1.57509e+45, global = -5.09557e+40, cumulative = -5.09557e+40
DICPCG:  Solving for p, Initial residual = 0.961166, Final residual = 1.84414, No Iterations 1001
time step continuity errors : sum local = 1.29718e+47, global = 5.31671e+42, cumulative = 5.26575e+42
ExecutionTime = 85.08 s  ClockTime = 87 s

Time = 0.02

Courant Number mean: 1.13079e+47 max: 1.72878e+50
DILUPBiCG:  Solving for Ux, Initial residual = 0.999672, Final residual = 3.36115, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.999739, Final residual = 1.97782, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999953, Final residual = 1.26137, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 26.5917, No Iterations 1001
time step continuity errors : sum local = 5.52811e+54, global = -1.50009e+47, cumulative = -1.50004e+47
DICPCG:  Solving for p, Initial residual = 0.968712, Final residual = 3.96145, No Iterations 1001
time step continuity errors : sum local = 6.76349e+56, global = 4.68529e+51, cumulative = 4.68514e+51
ExecutionTime = 102.04 s  ClockTime = 104 s

Time = 0.021

Courant Number mean: 6.15008e+56 max: 1.0711e+60
DILUPBiCG:  Solving for Ux, Initial residual = 0.999863, Final residual = 2.39706, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.999311, Final residual = 2.89499, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999239, Final residual = 9.1686, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 6.74239, No Iterations 1001
time step continuity errors : sum local = 9.93366e+62, global = 8.94398e+59, cumulative = 8.94398e+59
DICPCG:  Solving for p, Initial residual = 0.969226, Final residual = 5.91848, No Iterations 1001
time step continuity errors : sum local = 1.60358e+65, global = -3.91343e+61, cumulative = -3.82399e+61
ExecutionTime = 118.84 s  ClockTime = 121 s

Time = 0.022

Courant Number mean: 1.4642e+65 max: 1.56676e+68
DILUPBiCG:  Solving for Ux, Initial residual = 0.999892, Final residual = 14.4943, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.997566, Final residual = 314.253, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999563, Final residual = 47.8097, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 6.72161, No Iterations 1001
time step continuity errors : sum local = 2.74648e+72, global = 3.28068e+68, cumulative = 3.28068e+68
DICPCG:  Solving for p, Initial residual = 0.994044, Final residual = 1.4551, No Iterations 1001
time step continuity errors : sum local = 6.07386e+74, global = -3.00558e+70, cumulative = -2.97277e+70
ExecutionTime = 135.7 s  ClockTime = 139 s

Time = 0.023

Courant Number mean: 4.83037e+74 max: 2.49651e+78
DILUPBiCG:  Solving for Ux, Initial residual = 0.999758, Final residual = 1.13815, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.999584, Final residual = 6.9745, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999761, Final residual = 1.2188, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 4.16214, No Iterations 1001
time step continuity errors : sum local = 7.19249e+80, global = 3.93959e+77, cumulative = 3.93959e+77
DICPCG:  Solving for p, Initial residual = 0.974832, Final residual = 1.65162, No Iterations 1001
time step continuity errors : sum local = 5.25285e+82, global = 4.10531e+78, cumulative = 4.49927e+78
ExecutionTime = 153.07 s  ClockTime = 157 s

Time = 0.024

Courant Number mean: 4.6552e+82 max: 5.73544e+85
DILUPBiCG:  Solving for Ux, Initial residual = 0.999591, Final residual = 45.7348, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.996466, Final residual = 20.3214, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.998556, Final residual = 7.91727, No Iterations 1001
DICPCG:  Solving for p, Initial residual = 1, Final residual = 1.49843, No Iterations 1001
time step continuity errors : sum local = 6.52806e+88, global = -2.50005e+84, cumulative = -2.50005e+84
DICPCG:  Solving for p, Initial residual = 0.994329, Final residual = 47.8821, No Iterations 1001
time step continuity errors : sum local = 2.26097e+92, global = -1.25671e+88, cumulative = -1.25696e+88
ExecutionTime = 170.12 s  ClockTime = 174 s

Time = 0.025

Courant Number mean: 2.18709e+92 max: 1.36393e+95
DILUPBiCG:  Solving for Ux, Initial residual = 0.998666, Final residual = 9754.69, No Iterations 1001
DILUPBiCG:  Solving for Uy, Initial residual = 0.997946, Final residual = 7535.41, No Iterations 1001
DILUPBiCG:  Solving for Uz, Initial residual = 0.999833, Final residual = 303.156, No Iterations 1001
#0  Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#1  Foam::sigFpe::sigFpeHandler(int) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#2  Uninterpreted: 
#3  Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#4  Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam171/lib/linuxGccDPOpt/libfiniteVolume.so"
#5  
 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam"
#6  __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#7  
 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam"
Floating point exception
It seems like there is continuality problem somewhere...but i can't find it...
This is basic example...there should no be problem solving this...
I'm just afraid that i'm doing something wrong on basic stuff...(mesh or something like that)...but checkMesh returns "mesh OK"..
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Old   March 15, 2011, 15:18
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Martin
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Hi Petar,

your case works fine for me, tested on 1.6.x and 1.6-ext... can you try the attached case?

As a general rule you should keep the max courant number below 0.5 by choosing an appropriate time step. The rest of your settings seem to be fine.

Best regards

Martin
Attached Files
File Type: gz petar.tar.gz (2.3 KB, 115 views)
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Old   March 16, 2011, 10:20
Default
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Petar Zivkovic
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Thanks a lot for your effort martin...you gave me direction for solving my problem...i'm abuout to find out what you have done so i'll try to modify my files and see if i can tweak it...(it seems you have added some extra parameters and files then I have)...
your example works fine...it seems that it was problem with viscosity and time step at the same time...
tnx a lot!
if i had some questions or suggestions that may help someone in future, i'll post it here!
Petar.
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