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-   -   Inlet and Outlet (http://www.cfd-online.com/Forums/openfoam/87109-inlet-outlet.html)

 lmblanes April 11, 2011 13:49

Inlet and Outlet

Hi All

I am trying to setup a simple case with an Inlet and an Outlet.

I am used to WinAir, where you only input a Volumetric Flow (m3/s) and a directional Vector.

I am reviewing the Derived Patch Field Types...but I am confused about which one to use.

Could anyone help me on that?

Thanks

Another question I have is about the relationship between solvers and the different Patch Field Types.( I am using buoyanBoussinesqSimpleFoam, and the other steady state solver dealing with heat Transfer for buoyancy driven flows...)
Can I use anyone of the patch fields described in page U-133 ? or are they linked to a precise solver?

Thanks

Luis Blanes

 lmblanes April 11, 2011 15:13

Errors regarding Inlet and Outlet

Hello all
I tried to run a simulation with the following values at the U/0 directory

boundaryField
{
warm
{
type fixedValue;
value uniform (0 0 0);
}

cool
{
type fixedValue;
value uniform (0 0 0);
}

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

outlet
{
type fixedValue;
value uniform (0 0 1);

And I got that error.
Thanks
Can I input just two velocities in a patch just typing that in the U/0 directory??
Can the velocity vector point outside the domain??
Thanks

Starting time loop

Time = 0.1

DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.00451649, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 8.88538e-17, No Iterations 1
#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::DILUPreconditioner::calcReciprocalD(Foam::Fi eld<double>&, Foam::lduMatrix const&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 Foam::DILUPreconditioner::DILUPreconditioner(Foam: :lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#5 Foam::lduMatrix::preconditioner::addasymMatrixCons tructorToTable<Foam::DILUPreconditioner>::New(Foam ::lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#6 Foam::lduMatrix::preconditioner::New(Foam::lduMatr ix::solver const&, Foam::dictionary const&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#7 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so"
#8 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam171/lib/linuxGccDPOpt/libfiniteVolume.so"
#9
in "/opt/openfoam171/applications/bin/linuxGccDPOpt/buoyantBoussinesqSimpleFoam"
#10 __libc_start_main in "/lib/libc.so.6"
#11
in "/opt/openfoam171/applications/bin/linuxGccDPOpt/buoyantBoussinesqSimpleFoam"
Floating point exception
;

 The King April 12, 2011 05:49

Try to use zeroGradient for your outflow. Is the direction of the velocity in your inlet ok?

 lmblanes April 12, 2011 06:09

Quote:
 Originally Posted by The King (Post 303239) Try to use zeroGradient for your outflow. Is the direction of the velocity in your inlet ok?
Thanks The King.
Yes, the direction in the Inlet makes no sense.

I guess that you only need to input a velocity in the inlet and zeroGradient in the outlet.

Thanks

 lmblanes April 12, 2011 06:51

Inlet velocity is ok....

I have checked the case again...
I use buoyantBoussinesqSimpleFoam

Can anyone tell me how to input a simple Inlet and Outlet in using heatTransfer solvers?

U at inlet is ok (0 0 -1) as it is pointing inside the domain (can I use negative numbers?)

-----------------------------------------------------
boundary file

5
(
warm
{
type wall;
nFaces 390;
startFace 90580;
}
cool
{
type wall;
nFaces 390;
startFace 90970;
}
inlet
{
type patch;
nFaces 1;
startFace 91360;
}
outlet
{
type patch;
nFaces 1;
startFace 91361;
}
defaultFaces
{
type wall;
nFaces 5270;
startFace 91362;
}
----------------------------------------------------
U/0

dimensions [0 1 -1 0 0 0 0];
internalField uniform (0 0 0);
boundaryField
{
warm
{
type fixedValue;
value uniform (0 0 0);
}
cool
{
type fixedValue;
value uniform (0 0 0);
}
defaultFaces
{
type fixedValue;
value uniform (0 0 0);
}
inlet
{
type fixedValue;
value uniform (0 0 -1);
}
outlet
{
{
}
----------------------------------------------------

p/0

dimensions [0 2 -2 0 0 0 0];
internalField uniform 0;
boundaryField
{
warm
{
type buoyantPressure;
rho rhok;
value uniform 0;
}
cool
{
type buoyantPressure;
rho rhok;
value uniform 0;
}
defaultFaces
{
type buoyantPressure;
rho rhok;
value uniform 0;
}
inlet
{
type buoyantPressure;
rho rhok;
value uniform 0;
}
outlet
{
type buoyantPressure;
rho rhok;
value uniform 0;
}
}

 351Cleveland April 13, 2011 05:47

Hi lmblanes

Just wondering a little about your pressure setup. You might try keeping the outlet/internalField at uniform 0 and setting the rest to zeroGradient. My experience is only really with simpleFoam, so I hope this helps.
Also, yes you can use negative numbers for velocity as long as you're sure its in the right direction.

Dom

 lmblanes April 13, 2011 05:57

Thanks!
I have seen lots of cases where there is an Inlet and the "Outlet" is just a free pressure boundary...

What do you mean with "in the right direction"? Is there some rule?

I wonder if I can do something like this

________________
I I
I I
Inlet(1m3/s) ---> Outlet(0.9 m3/s) --->
I I
I I
I Opening to atmosphere
I_______________ I

Thanks

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