How to make a region to patch a bubble
 

Hello.
If you answer my question, I really appreciate your kindness.

My question; I can't make a region to patch a bubble in the most finest grids.

I study bubble dynamics by using VOF method.
To meke the calculation cost low I used three types grids like Figure.1.
To make the grids I used adjust option in Fluent.

Thank you for your reading.

Just an idea, you can add an inlet at below of finer grid, you can define only air phase that inlet. And mass-flow (or velocity) inlet is bigger than 0 for a short time.

Or you can add different zone in design modeler inside finer grid zone. Similar with this:

https://www.youtube.com/watch?v=nN-KO6cEskE