Poiseuille's law

The Poiseuille's law (or the Hagen-Poiseuille law also named after Gotthilf Heinrich Ludwig Hagen (1797-1884) for his experiments in 1839) is the physical law concerning the voluminal laminar stationary flow ΦV of incompressible uniform viscous liquid (so called Newtonian fluid) through a cylindrical tube with the constant circular cross-section, experimentally derived in 1838, formulated and published in 1840 and 1846 by Jean Louis Marie Poiseuille (1797-1869), and defined by:

Curiosity

The law itself shows what an interesting field this is, as the Darcy-Weisbach equation was studied by a number of other scientists, including Chézy, Weisbach, Darcy, Poiseuille, Hagen, Reynolds, Fanning, Prandtl, Blasius, von Kármán, Nikuradse, Colebrook, White, Rouse, and Moody.

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Also note in the formula how strongly the flow depends on the radius. If all else is held constant, a doubling of the radius of the channel results in a sixteen-fold increase in the flow.

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