Fluid Mechanics seventh edition by Frank M. White · Problem P6.15
Viscous Flow in Ducts — Frank M. White
Physics — Fluid Mechanics · laminar-pipe-flow
Problem
Professor Gordon Holloway and his students at the University of New Brunswick went to a fast-food emporium and tried to drink chocolate shakes (ρ≈1200 kg/m3, μ≈6 kg/m⋅s) through fat straws 8 mm in diameter and 30 cm long. (a) Verify that their human lungs, which can develop approximately 3000 Pa of vacuum pressure, would be unable to drink the milkshake through the vertical straw. (b) A student cut 15 cm from his straw and proceeded to drink happily. What rate of milkshake flow was produced by this strategy?