# simpleFoam /water in pipes/ how to obtain and tune the solution?

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

March 29, 2012, 10:40
simpleFoam /water in pipes/ how to obtain and tune the solution?
#1
New Member

Peter
Join Date: Apr 2010
Location: Brno, Czech Republic
Posts: 24
Rep Power: 9
Dont know how to hide or delete this for now, but i found mismatched BC. But maybe I will need help later. Thanks for visit.

Hello,

I am solving water flowing in pipe in steadyState by simpleFoam. I have Re~20000. Velocities 1÷2m/s. I am unable to converge with my case. I did a comparison of case with laminar vs. k-eps regime, and tetra vs. polyhedral mesh (produced by polyDualMesh from that tets). Could you help me to tune up fvSchemes and fv Solution, please ? Or is it grid or BC related issue ?

I have read and tried several ideas written on the forum but no big success. I also divided the case in solving bended knee only, T-juction only. They have converged, but now the solution blows up e.g. on k and epsilon bounding and time step continuity error at some point of computation. I would like to compute temperature fields later on, but I am unable to solve flow for now.

my case:

boundaries are like: green inlet (hot water); red outlet (hot water); red inlet(cold water); blue outlet(cold water). Hot outlet and cold inlet is the same diameter and mass flow.
Files from system folder are attached. CheckMesh for both meshes as well. BCs are in the end of post. Now I will show resiaduals. Maybe somebody knows what happens there.

Thank you

http://soonic.cesnak.org/cfd/lam_pol...b_polyTurb.png

p
Code:
internalField   uniform 0;

boundaryField
{
inh
{
}
inc
{
}
outh
{
type            fixedValue;
value           uniform 0;
}
outc
{
}
stena
{
}
U
Code:
internalField   uniform (0 0 0 );

boundaryField
{
inh
{
type            fixedValue;
value           uniform (0.504 0 0); //Value is half scaled for laminar case
}
outh
{
type            fixedValue;
value           uniform (0 1.7654 0); //Value is half scaled for laminar case
}
inc
{
type            fixedValue;
value           uniform (0 -1.7654 0); //Value is half scaled for laminar case
}
outc
{
}
stena
{
type            fixedValue;
value           uniform (0 0 0);
}
}
k
Code:
internalField   uniform 0.004;

boundaryField
{
inh
{
type            turbulentIntensityKineticEnergyInlet;
intensity       0.04726;
U               U;
phi             phi;
value           uniform 0.000852;
}
outh
{
type            turbulentIntensityKineticEnergyInlet;
intensity       0.04229;
U               U;
phi             phi;
value           uniform 0.00836;
}
inc
{
type            turbulentIntensityKineticEnergyInlet;
intensity       0.04229;
U               U;
phi             phi;
value           uniform 0.00836;
}
outc
{
}
stena
{
type            kqRWallFunction;
value           uniform 0.001;
}
epsilon
Code:
internalField   uniform 100;

boundaryField
{
inh
{
type            turbulentMixingLengthDissipationRateInlet;
mixingLength    0.034678;
phi             phi;
k               k;
value           uniform 0.0001179;
}
outh
{
type            turbulentMixingLengthDissipationRateInlet;
mixingLength    0.02407;
phi             phi;
k               k;
value           uniform 0.0052217;
}
inc
{
type            turbulentMixingLengthDissipationRateInlet;
mixingLength    0.02407;
phi             phi;
k               k;
value           uniform 0.0052217;
}
outc
{
}
stena
{
type            epsilonWallFunction;
value           uniform 0.001;
}
}
Attached Files
 checkMesh.poly.txt (2.9 KB, 4 views) checkMesh.tet.txt (2.9 KB, 1 views) fvSolution.txt (2.8 KB, 9 views) fvSchemes.txt (2.0 KB, 10 views)

Last edited by soonic; March 29, 2012 at 14:30.

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

All times are GMT -4. The time now is 00:40.