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## Main Question or Discussion Point

Hello Forum,

The important Poiseuille equation tells us that there must be a pressure difference in an incompressible AND viscous Newtonian fluid in laminar flow flowing through a cylindrical pipe of constant cross section and radius R and length L. Viscosity hinders fluid motion.

But even in the case of a perfect fluid (zero viscosity) a pressure difference between the two ends of the tube is needed to set the fluid into motion. But the Poiseuille equation seems to tell us that no pressure is needed to maintain an inviscid fluid into motion...I am confused..

thanks,

fog37

The important Poiseuille equation tells us that there must be a pressure difference in an incompressible AND viscous Newtonian fluid in laminar flow flowing through a cylindrical pipe of constant cross section and radius R and length L. Viscosity hinders fluid motion.

But even in the case of a perfect fluid (zero viscosity) a pressure difference between the two ends of the tube is needed to set the fluid into motion. But the Poiseuille equation seems to tell us that no pressure is needed to maintain an inviscid fluid into motion...I am confused..

thanks,

fog37