Poiseuille's Law (also Hagen-Poiseuille equation) calculates the fluid flow through a cylindrical pipe of length L and radius R.
The poiseuille's equation is:
V = π * R4 * ΔP / (8η * L)
R: Cross-sectional radius of the pipe, in meter
ΔP: Pressure difference of two ends, in Pascal
η: Viscosity of the fluid, in Pa.s
L: Pipe length, in meter
V: Volumetric Flow Rate, in m/s