CFD Online Discussion Forums - Strange averaging in directMappedFixedValue BC

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Strange averaging in directMappedFixedValue BC

Dear All,

while trying to derive my own BC from the direct mapped BC, i was wondering why there are two different averaging possibilities:

Code:

   if (setAverage_)

    {

        Type averagePsi =

            gSum(this->patch().magSf()*newValues)

           /gSum(this->patch().magSf());



        if (mag(averagePsi)/mag(average_) > 0.5)

        {

            newValues *= mag(average_)/mag(averagePsi);

        }

        else

        {

            newValues += (average_ - averagePsi);

        }

    }

Any Idea about the streching if the average differs to much?

Have FUN!

Quote:

Originally Posted by woody (Post 264335)

Dear All,

while trying to derive my own BC from the direct mapped BC, i was wondering why there are two different averaging possibilities:

Code:

   if (setAverage_)

    {

        Type averagePsi =

            gSum(this->patch().magSf()*newValues)

           /gSum(this->patch().magSf());



        if (mag(averagePsi)/mag(average_) > 0.5)

        {

            newValues *= mag(average_)/mag(averagePsi);

        }

        else

        {

            newValues += (average_ - averagePsi);

        }

    }

Any Idea about the streching if the average differs to much?

Have FUN!

Hi guys,
I am successfully using the mapped BC for LES of turbulent flow through a 90deg bend, with the mapping region located in an (extended) straight inlet section. I switched on averaging of velocity to obtain my desired bulk velocity.

While running the simulation, I assumed that OF always computes the new velocities according to the above else statement, using the difference between the desired average and the current velocities. Then I checked the corresponding code and I'm also a bit confused by the same the if statement, specifically by the condition and the first correction method.

Any ideas?

Thanks,
Florian