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FOAM FATAL ERROR: Continuity error cannot be removed by adjusting the outflow.

Hello,
I'm trying to run a simulation it gives the following error:

Code:

--> FOAM FATAL ERROR: 

Continuity error cannot be removed by adjusting the outflow.

Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow.

Total flux              : 105.971

Specified mass inflow   : 546831

Specified mass outflow  : 0

Adjustable mass outflow : 0

The geometry consists in a mixing elbow with constant diameter on the bent tube.

This are the initial conditions for velocity and pressure:
Velocity

Code:

dimensions      [0 1 -1 0 0 0 0];



internalField   uniform (0 0 0);



boundaryField

{

    wall

    {

        type            noSlip;

    }



    inletSmall

    {

//        type            zeroGradient;

        type            fixedValue;

        value            uniform (0 1.2 0);    

    }



    inletBig

    {

//        type            zeroGradient;

        type            fixedValue;

        value            uniform (0.4 0 0);

    }



    outlet

    {

        type            zeroGradient;

    }

}

Pressure

Code:

dimensions      [0 2 -2 0 0 0 0];



internalField   uniform 0;



boundaryField

{

    wall

    {

        type            zeroGradient;

    }



    inletSmall

    {

//        type            fixedValue;

//        value            uniform 1010.325;

        type            zeroGradient;

    }



    inletBig

    {

//        type            fixedValue;

//        value            uniform 1010.325;

        type            zeroGradient;

    }



    outlet

    {

//        type            fixedValue;

//        value            uniform 0;

        type            zeroGradient;

    }

}

If i use the commented options (zeroGradient velocity and set pressure) no errors are given.

Does anyone know how to help me?

Hi,
you could try to set the pressure outlet boundary to
type fixedValue;
value uniform 0;
Keep the other settings as you posted it here.

Found the solution.
The error was that in the output patch both velocity and pressure were set to zeroGradient.
By setting an outlet pressure the solution could be found!
Thanks anyway

Just found out. Thanks anyway HorstPeter!

Hello

I am new comer to open Foam. could you please somebody help me for this alarm.

--> FOAM FATAL IO ERROR:
keyword inletValue is undefined in dictionary "/home/farshad/Desktop/elbow/0/k.boundaryField.pressure-outlet-7"

file: /home/farshad/Desktop/elbow/0/k.boundaryField.pressure-outlet-7 from line 35 to line 36.

From function dictionary::lookupEntry(const word&, bool, bool) const
in file db/dictionary/dictionary.C at line 402.

FOAM exiting

This alarm says that you haven't defined a value for k.
This might be a better thread for you:
https://www.cfd-online.com/Forums/op...condition.html

Quote:

Originally Posted by mgab (Post 629857)

Found the solution.
The error was that in the output patch both velocity and pressure were set to zeroGradient.
By setting an outlet pressure the solution could be found!
Thanks anyway

hi

how did you set your BC for outlet I become the same error message but I couldn't fix it
thx for your help

Hi getting a same error, can anybody help ??

velocity

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
upperWall
{
type noSlip;
}
frontAndBack
{
type noSlip;
}
lowerWall
{
type noSlip;
}

inlet1
{
type fixedValue;
value uniform (8 0 0);
}
inlet2
{
type fixedValue;
value uniform (10 0 0);
}
outlet
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}
defaultFaces
{
type empty;
}
}

Pressure [p_rgh]

dimensions [1 -1 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
upperWall
{
type fixedFluxPressure;
value uniform 0;
}

frontAndBack
{
type fixedFluxPressure;
value uniform 0;
}

lowerWall
{
type fixedFluxPressure;
value uniform 0;
}
inlet1
{
type fixedFluxPressure;
value uniform 0;
}
inlet2
{
type fixedFluxPressure;
value uniform 0;
}
outlet
{
type fixedFluxPressure;
value uniform 0;
}

defaultFaces
{
type empty;
}
}