Hi I have a question about the warning “a vortex crosses the pressure opening”

I get this warning at the few first iterations of a simulation, after a few iterations the warning goes away.

What does this mean?

Does it mean that it happens or it doesn’t happen?

It is important to me because I’m planning a wood stove and I don’t want smoke getting in the room that the stove is installed in.

The simulation is NOT time dependat

Thanks

Ido