Turbulent Flow Poseuille Law Equation

Fluid Flow Table of Contents
Hydraulic and Pneumatic Knowledge

Fluid Power Equipment

Turbulent Flow Poseuille Law Equation

Flow descriptions such as Poiseuille's law are valid only for conditions of laminar flow . At some critical velocity, the flow will become turbulent with the formation of eddies and chaotic motion which do not contribute to the volume flowrate. This turbulence increases the resistance dramatically so that large increases in pressure will be required to further increase the volume flowrate.

Turbulent flow is characterized by the irregular movement of particles of the fluid. There is no definite frequency as there is in wave motion. The particles travel in irregular paths with no observable pattern and no definite layers.

Experimental studies have characterized the critical velocity for a long straight tube in the form

Vc = Rn/2pr


Vc = Critical Velocity
n = Viscosity (poise)
p = density (gm/cm3)
r = Reynolds Number