Theory of lift
 

How wings really work - Research - University of Cambridge

I always show the student by placing a rule, which roughly wing shaped and spoon in the flow of water from a tap. The curved back of spoon is draw into the flow of water.
What would happen if the the tap and spoon were put in a vacuum?

Exactly the same, because in your expaeriment, the water takes the place of the air. It makes absolutely no difference what happens "outside" your setup!

It is interesting that the article which is explaining Coander effect doesn't actually mention that. There are many good articles on the subject