Most Revolutionary Physics Research Ever

http://ift.tt/H36Gso



Abstract:

Quote:

Many urological studies rely upon animal models such as rats and pigs whose urination physics and correlation to humans are poorly understood. Here we elucidate the hydrodynamics of urination across five orders of magnitude in animal mass. Using high-speed videography and flow-rate measurement at Zoo Atlanta, we discover the “Law of Urination,” which states animals empty their bladders over nearly constant duration of 21 ± 13 seconds. This feat is made possible by larger animals having longer urethras, thus higher gravitational force and flow speed. Smaller mammals are challenged during urination due to high viscous and surface tension forces that limit their urine to single drops. Our findings reveal the urethra constitutes as a flow-enhancing device, enabling the urinary system to be scaled up without compromising its function. This study may help in the diagnosis of urinary problems in animals and in inspiring the design of scalable hydrodynamic systems based on those in nature.

Methods:

Quote:

We film urination of sixteen animals (Figure 1(a)-(d)) and obtained twenty-eight urination videos from YouTube. Figure 1(h) shows the duration of urination across 6 orders of magnitude of animal mass from 0.03 kg to 8000 kg. Despite this large range, the duration remains nearly constant, T = 21 ± 13 seconds (N=32) for all animals heaver than 3 kg. This constancy of emptying time is quite a feat upon consideration of the substantial bladders of larger animals. The urination duration for both jetting and dripping regime are modeled in the Supplement.

Enjoy :razz:

Most Revolutionary Physics Research Ever