- Poiseuille's law
**Poi·seuille's law pwä-'zə(r)z-, -'zwēz-, -'zə-ēz-***n*a statement in physics: the velocity of the steady flow of a fluid through a narrow tube (as a blood vessel or a catheter) varies directly as the pressure and the fourth power of the radius of the tube and inversely as the length of the tube and the coefficient of viscosity**Poi·seuille pwȧ-zœy Jean-Léonard-Marie***(1797-1869)*French physiologist and physician. Poiseuille is best known for his research on the physiology of the circulation of blood through the arteries. He published his research in an 1828 dissertation in which he demonstrated that blood pressure rises and falls on expiration and inspiration. His interest in blood circulation led him to study the flow rates of other fluids. In 1840 he formulated the law regarding the flow rate for the laminar flow of fluids in circular tubes. In 1847 he published the results of further experiments using ether and mercury. Gotthilf Hagen, a German hydraulic engineer, discovered Poiseuille's law independently in 1839.* * *

an equation describing the volume flow rate*(F)*of a liquid through a capillary tube:where

*P*is the pressure drop along the tube,*R*is the radius and*L*the length of the tube, and η is the viscosity of the fluid.

*Medical dictionary.
2011.*