[dhein]

Hello,


I'm pretty new in using Star-CCM+ or in General a CFD-Software.


I want to run a transient analysis where I want to implement a stopping criteria that is activated when the total kinetic energy in the system is not varying more than a certain amount anymore.


For that I defined a Field Expression called Kinetic Energy per Volume, which I defined as:


0.5 * dot($${Velocity},$${Velocity}) * ${Density}



Now my problem is that I receive an error message when I want to run the expression (definition is my field function) which says:

Cannot evaluate field function Velocity


I hope I was able to communicate my problem and that somebody is able to help me.

[cwl]

What type is the report?

[dhein]

I used an Expression Report. It's value I wanted to use for a Volume Integral Report afterwards.




Edit: When I tried to use a Volume Integral Report in first place, I wasn't able to choose my Field Function in that kind of Report. But now it somehow worked. Nevertheless I am curious about why the field function velocity cannot be evaluated in the case of an Expression Report.

[cwl]

I used an Expression Report.

Exactly. Expression should result in a single scalar value (number).
But your Field Function is a function defined in every cell - there is no single value to be reported.
So - just go agead with the Volume Integral Report and it will work fine.

[dhein]

Thank you very much, cwl!
That makes sense. Like given.

[cwl]

You are very welcome :>

[cwl]

When I tried to use a Volume Integral Report in first place, I wasn't able to choose my Field Function in that kind of Report

That usually indicates that there is something wrong with the Field Function.

You can always check your Field Function by plotting it on some plane section.
If it is not available there - then check Field Function definition itself.