Fan is pushing in the front and sucking from the back

[Herman Trivilino]

@Herman Trivilino, do you disagree with the illustration? It clearly depicts the fluid to be flowing through the ear tube in order to reach the ear canal.

Well, it's not an illustration of a tympanostomy tube being used in a way that's consistent with my understanding of the situation. Perhaps I've got it all wrong but I'm under the impression that air flows into the ear from the atmosphere through that tube.

Maybe my example is a poor choice. It was meant to illustrate the same principle as a drinking straw or a vacuum cleaner. These devices rely on atmospheric pressure to push a fluid through a tube. Without the atmosphere to do the pushing you could suck as hard as possible on the other end of the tube and no fluid would flow. The mechanism responsible for the functioning of these devices is the push from the atmosphere, not a pull from the other end of the tube.

This is the way their function is described in every college-level introductory physics textbook that describes them.

 

[A.T.]

Without the atmosphere to do the pushing you could suck as hard as possible on the other end of the tube and no fluid would flow.

It depends on what you mean by 'suck'.

Trees can pull water much higher than the 10m it gets pushed up by atmosphere. And most of the upwards force to achieve that is applied to the fluid column at the very top, in the very tiny pores of the leaves:
https://www.physicsforums.com/threa...nsport-of-water-to-the-apex-of-a-tree.1078459

That's possible because, unlike gases, fluids can have negative absolute pressures, or internal 'tension', due to cohesive forces. So it is possible to pull and move a fluid, without any pushing on the other side.

 

[Herman Trivilino]

It depends on what you mean by 'suck'.

Trees can pull water much higher than the 10m it gets pushed up by atmosphere.

True for liquids. Capillary action. Hadn't thought of that. Not relevant to the OP's situation. I give up.