[a_slow_old_man]

Hello cfd-online.com

I am trying to use swak4foam for a project, but I seem to miss an important step.

I use Ubuntu14.04LTS and OpenFoam2.4.0

I installed the swak4foam version for OF2.0 and higher

svn checkout svn://svn.code.sf.net/p/openfoam-extend/svn/trunk/Breeder_2.0/libraries/swak4Foam/ swak4Foam_2.x

Then I followed these instructions:
https://openfoamwiki.net/index.php/I...14.04_to_15.10

But when I try to use this function in my controlDict

functions
{

    pressureDrop
    {
        type patchExpression;
        variables ( "pOut{patch'outlet}=sum(p*area())/sum(area());");
        accumulations (
           min
           max
        );
        patches (
            inlet
        );
        expression "p-pOut";
        verbose true;
    }
}

I get the following error

--> FOAM FATAL ERROR: 
Unknown function type patchExpression

Valid functions are : 

4
(
patchProbes
probes
sets
surfaces
)



    From function functionObject::New(const word& name, const Time&, const dictionary&)
    in file db/functionObjects/functionObject/functionObject.C at line 92.

FOAM exiting

I tried to fix this by following the advice from various threads about installation problems with swak4foam and added to my bashrc the line:

export SWAK4FOAM_SRC=$HOME/swak4Foam_2.x/Libraries/

but still the same.

I am relativly new to Ubuntu and openFoam. Any help is deeply appreciated

[a_slow_old_man]

If anyone in future has the same misconceptions as I do.

You can't just put in the functionObjects from swak4Foam in the ControlDict of a random case. You need the .libs too.

There is a folder "Examples" in the "./swak4Foam/" main folder. Pick your desired option and C&P them into your file.