Talk:2775: Siphon

My understanding was that siphoning can essentially be explained by the Bernoulli equation? There is a difference in potential energy between the upper and lower container so it flows. The weight of water in the downhill part of the tube pulls water up the uphill section of the tube (think like a vacuum), and so on until there's either no difference in head or no more water. Siphoning will work with any diameter tube. 172.70.91.151 15:43, 12 May 2023 (UTC)

That's right. The only mention of capillary action in the siphon wikipedia article is when talking about phenomenon that *isn't* a siphon. Barmar (talk) 16:15, 12 May 2023 (UTC)

Agree, capillary action does not seem to be referenced or implied in the comic, presenting only the (not "functioning") siphon phenomenon. 172.68.134.142 16:23, 12 May 2023 (UTC)

Seconded/thirded. Capillary action isn't even what they were expecting. The small amount of water in the lowe receptical indicates they correctly filled the tube, but then as the longer length drained it did not then induce further flow up and over through the shorter length. e.g. nature no longer abhored the resulting vacuum (or there was increased negative-pressure vapourisation, beyond that previously expected, or other method of seepage 'airlock'-breaking) and thus the short-end also drained straight back out again instead of becoming a potentially self-sustaining inflow to the whole siphoning setup.

If the upper end got restricted (say by touching the side of the bucket) the loss of flow would allow air to enter the bottom end and drain out the tube. I've done this. :-( RIIW - Ponder it (talk) 19:07, 12 May 2023 (UTC)

While the capilliary action element could induce the start of a rather limited 'empty' siphon setup to start (maybe, I'd have doubts about the 'fluid friction' actually acting against the gravity-feed part, once the surface-tension bit has "climbed the mountain" and started to merely seep out of the other end, almost incidentally, for a sufficiently thin tubing where CA is a significant factor), this suddenly failing for whatever reason (surface-tension effects being nullified) wouldn't then send a token amount of water into the low bucket, nor particularly stop unrelated siphon-flow from continuing properly (in fact, suddenly 'interaction-free' liquid and tubing might siphon faster, with effectively zero fluid boundary effects dragging on the induced flow).

But perhaps someone with more QFD experience could explain where my assessment is wrong. So not going to personally rewrite the current Explanation intro just now. 172.70.162.161 16:21, 12 May 2023 (UTC)

I'd like to contribute as one more data point. I also don't see capillary action as being relevant. In particular, as another commenter said, the water in the lower bucket quite clearly supports the idea that the siphon effect was the subject of the characters' confusion. How else is Randall supposed to depict the siphon effect anyway? I agree that the drawing alone could also suggest capillary action is what's being investigated, but I don't think it suggests that the caption has incorrectly referred to it as the siphon effect. 172.71.254.100 18:44, 12 May 2023 (UTC)