volume flow rate through an opening?

Hi Patrick,

Have you 'turned off' the body / lid in Component Control ?

You should then be able to apply a surface goal.

Hi Patrick,

For the Surface Goal, you shouldn't need to create a separate surface; you can just use the face of the lid.

If the location of interest for extracting the VFR is on the lid's internal surface, then pick that face. Otherwise, you can define a thin solid body on flow path (make sure to exclude it from analysis). Thereafter, you can use its faces for defining goal/extracting results etc.

As a side note: surfaces are not valid entities in flow simulation.