Question

poiseuille's formula

Answer 1

In nonideal fluid dynamics, the Hagen–Poiseuille equation, also known as the Hagen–Poiseuille  law, Poiseuille law or Poiseuille equation, is a physical law that gives the pressure drop in an incompressible and Newtonian fluid in laminar flow flowing through a long cylindrical pipe of constant cross section.

In the above equation,

ΔP is the pressure difference between the two ends,
L is the length of pipe,
μ is the dynamic viscosity,
Q is the volumetric flow rate,
R is the pipe radius.