[mwmalkawi]

I have a multiphase pipe flow case with one inlet (inlet1), two outlets (outlet1 and outlet2) and one vent shaft (atmosphere) as per screen shot below attached with turbulent flow k-e model enabled
When run the solution and simulate results in preview it shows the flow when reaches outlet 1 and 2 it starts to reverse as if there is wall at these outlets that is preventing the flow to exit you can see the simulation video attached.
3D Model.png

flow at outlets.png

reverse flow outlet1 .png

reverse flow outlet2 .jpg
I really appreciate the help in this one as I believe something wrong with the settings of my boundary conditions as I have tried millions of combinations and options for BC for the last 6motnhs.

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object alpha.water;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{

wall
{
type zeroGradient;
}


outlet1
{
type inletOutlet;
inletValue uniform 0;
value uniform 0;
}

outlet2
{
type inletOutlet;
inletValue uniform 0;
value uniform 0;
}

inlet1
{
type inletOutlet;
inletValue uniform 1;
value uniform 1;
}


}

// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
object p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [1 -1 -2 0 0]; // or [0 2 -2 0 0 0 0];
internalField uniform 0;
boundaryField
{

wall
{
type zeroGradient;
}

outlet1
{
type totalPressure;
p0 uniform 0;
value uniform 0;
}

outlet2
{
type totalPressure;
p0 uniform 0;
value uniform 0;
}

inlet1
{
type fixedFluxPressure;
value uniform 0;
}

}
// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volVectorField;
location "0";
object U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);
boundaryField
{
wall
{
type fixedValue;
value uniform (0 0 0);
}

inlet1
{
type surfaceNormalFixedValue;
refValue uniform -1;
}

outlet1
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}
outlet2
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}

}

// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object epsilon;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -3 0 0 0 0];

internalField uniform 0.0027;
boundaryField
{
wall
{
type epsilonWallFunction;
value uniform 0.00027;
}

outlet1
{
type zeroGradient;
}
outlet2
{
type zeroGradient;
}


inlet1
{
type fixedValue;
value uniform 0.025;
}


}

// ************************************************** *********************** //

FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object k;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -2 0 0 0 0];

internalField uniform 0.009;
boundaryField
{
wall
{
type kqRWallFunction;
value uniform 0.0052;
}

outlet1
{
type zeroGradient;
}
outlet2
{
type zeroGradient;
}


inlet1
{
type fixedValue;
value uniform 0.002;
}
}

// ************************************************** *********************** //
FoamFile
{
version 2.0;
format ascii;
class volScalarField;
location "0";
object nut;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions [0 2 -1 0 0 0 0];

internalField uniform 0;
boundaryField
{
wall
{
type nutkWallFunction;
value uniform 0;

outlet1
{
type calculated;
value uniform 0;
}
outlet2
{
type calculated;
value uniform 0;
}


inlet1
{
type calculated;
value uniform 0;
}


}

// ************************************************** *********************** //

[fresty]

You may want to link/attach your case folder to evoke more specific support.

[ssa_cfd]

why did you use inletOutlet for the inlet patch in alpha.water and totalPressure for outlet patch in p_rgh.





check the water channel tutorial and modify your boundary conditions.

[mwmalkawi]

Originally Posted by ssa_cfd

why did you use inletOutlet for the inlet patch in alpha.water and totalPressure for outlet patch in p_rgh.





check the water channel tutorial and modify your boundary conditions.

I have done all possible cases you would imagine i am attaching to you an excel sheet showing you all cases of BC i have used.

[mwmalkawi]

Thank you Fresty please see below the zip file for the Case i appreciate anyone who can asist

[Ferran]

I'm pretty sure it is because in the U file in the 0 folder, you have set the outlets as "type pressureInletOutletVelocity; value uniform (0 0 0);" so it is acting with velocity=0. Try setting it as a "type zeroGradient;" or another outlet boundary condition.
Let me know if it works, otherwise I could share my boundary conditions settings, I have been running some multiphase simulations.
On the case files, the mesh or the dictionaris to generate the mesh are missing for us to try your case.

[mwmalkawi]

Thank you Ferran will you please share yours if you have a similar pipe flow case with one inlet and two outlets...many thanks

[Ferran]

I have run it with a simple geometry, 1 water inlet and 2 pressure outlets. There is a readme listing all the changes I've done with your files as a template.
I do not get the recirculation that you mention, though I have not seen the results of your case.

It took around one hour to calculate with 4 processors, 17.3s of real time.

Without results (~1 MB)
https://drive.google.com/file/d/1IWa...ew?usp=sharing

With results and animation (~1 GB)
https://drive.google.com/file/d/1_D4...ew?usp=sharing

You should be able to download, otherwise tell me.

Hope it is useful.

[Bodo1993]

Originally Posted by Ferran

I have run it with a simple geometry, 1 water inlet and 2 pressure outlets. There is a readme listing all the changes I've done with your files as a template.
I do not get the recirculation that you mention, though I have not seen the results of your case.

It took around one hour to calculate with 4 processors, 17.3s of real time.

Without results (~1 MB)
https://drive.google.com/file/d/1IWa...ew?usp=sharing

With results and animation (~1 GB)
https://drive.google.com/file/d/1_D4...ew?usp=sharing

You should be able to download, otherwise tell me.

Hope it is useful.

Hi Ferran,

Kindly, I would appreciate your assistance. I have simple 2D vertical channel flow with single inlet and single outlet. Fluid 1 initially fills the channel and Fluid 2 is pumped from below (fluids have different densities and viscosities). I have an issue at the outlet - the fluids exists from just a small portion of the outlet boundary.

For the outlet boundary conditions, I use: pressureInletOutletVelocity for U, totalPressure for P and zeroGradient/inletOutlet for alpha.

I am wondering if you can assist me on this case. Thanks and I look forward to hearing from you.

[Nic86]

hello everyone,
sorry for the intrusion but could anyone try to answer to my thread?

InterFoam simulation - mesh setup

It's a quite similar case to the one of this post but my problem is that the water reaches the atmosphere patch and i do not know how to solve it.

Thank you