The derivation of this expression from the Darcy-Weisbach equation combines the formula for the energy head loss factor with the equation for the kinematic viscosity.  Wilberforce's variation is a modification of Hagenbach's equation, which contained a coefficient of kinetic friction that allowed it to be extended to turbulent flow.  One of its uses is to calculation of the number of capillaries in the body.  Stated delta
The derivation of this expression from the Darcy-Weisbach equation combines the formula for the energy head loss factor with the equation for the kinematic viscosity.  Wilberforce's variation is a modification of Hagenbach's equation, which contained a coefficient of kinetic friction that allowed it to be extended to turbulent flow.  One of its uses is to calculation of the number of capillaries in the body.  Stated delta-P equals 8-Q-mu-L divided by pi-R to the fourth power, FTP, name this equation, analogous to Ohm's Law for hydraulics, which predicts laminar flow through a uniform pipe.
The derivation of this expression from the Darcy-Weisbach equation combines the formula for the energy head loss factor with the equation for the kinematic viscosity.  
Poiseuille's law or equation