[Robert A Cook PE]

It will, in the physical world depend on the diameter of the two tubes at the right angle, and the speed the coffee is poured. Pour slow enough, with all the joints clean and at right angles (so the there is an air path out of the lower lower tube), and the coffee will flow as described.

Pour it quick enough, and it will trap air and stall out. But the trapped air will bubble through the trapping tubes eventually, if the tubes are big enough not to trap the bubbles with a meniscus effect.

[MD Expat in PA]

Thanks!