[HN Gopher] A new solution for the "reverse sprinkler" problem
       ___________________________________________________________________
        
       A new solution for the "reverse sprinkler" problem
        
       Author : Archelaos
       Score  : 21 points
       Date   : 2024-02-03 10:44 UTC (1 days ago)
        
 (HTM) web link (arstechnica.com)
 (TXT) w3m dump (arstechnica.com)
        
       | syllablehq wrote:
       | Hmm, is it possible that this could be partly caused because the
       | water gets sucked not just directly down the pipe, but around the
       | lip of the pipe opening... and one edge of the pipe opening is
       | further away from the center axis of rotation (of the whole
       | sprinkler) than the other end of the pipe opening. I'd think that
       | whether or not this would have an effect could be easily tested
       | by varying sizes of the pipe opening or how far away the opening
       | was from the center to see if it made a difference -- even if the
       | bends in the pipe were the same (the authors seem to attribute
       | the whole effect to the bends in the arms).
        
         | syllablehq wrote:
         | I'll add that this could become particularly important in the
         | 4d case once the sprinkler starts moving. Cause when it's
         | still, the pressure gradient will create a partial-torus like
         | shape around opening, but once it starts rotating, the outer
         | side (rotating around the sprinkler's axis) of the 4D version
         | of this shape has a larger diameter than the inside. So the
         | inner side will be more affected by the environmental water's
         | momentum state than the outside which has more water mass in
         | it's scope rotating around the sprinkler axis.
        
       | Cheer2171 wrote:
       | Why can't you just submerge the sprinkler in water and reverse
       | the flow?
        
         | seventytwo wrote:
         | That's what they did
        
         | syllablehq wrote:
         | Yes that is the experiment. I think when you do that it doesn't
         | move at all because the effect is tiny so will normally be
         | nullified by friction? And I think the research used very low
         | friction so they could observe the small effect.
        
       ___________________________________________________________________
       (page generated 2024-02-04 23:00 UTC)