[yeharav]

Dear foamers,

I would like to set up the boundary condition for P that is coupled to the variable
T. For example:

dP
----- = - T
dn

on a specific patch (lets say floor)

I did try,
floor
{
type groovyBC;
gradientExpression "-thetaFloor";
fractionExpression "0";
variables "thetaFloor{floor}=T;";
value uniform 0;
}

But then I get

--> FOAM Warning :
From function ExpressionResult::getUniformInternal(const label size,bool noWarn)
in file ExpressionResult/ExpressionResultI.H at line 332
The minimum value -47.6319 and the maximum 41.4594 differ. I will use the average -0.120515

every time step.

What am I doing wrong?

[gschaider]

Originally Posted by yeharav

Dear foamers,

I would like to set up the boundary condition for P that is coupled to the variable
T. For example:

dP
----- = - T
dn

on a specific patch (lets say floor)

I did try,
floor
{
type groovyBC;
gradientExpression "-thetaFloor";
fractionExpression "0";
variables "thetaFloor{floor}=T;";
value uniform 0;
}

But then I get

--> FOAM Warning :
From function ExpressionResult::getUniformInternal(const label size,bool noWarn)
in file ExpressionResult/ExpressionResultI.H at line 332
The minimum value -47.6319 and the maximum 41.4594 differ. I will use the average -0.120515

every time step.

What am I doing wrong?

This is a BC for the floor. So no need to access it as a "far away patch". Just write gradientExpression "-T" and you should be fine.

The problem of remote variables having to be uniform was discussed numerous times (I won't repeat this here especially as you don't need a remote)

[yeharav]

Thanks it works.