An Investigation of the Basic Physics of Irrigation in Urology and the Role of Automated Pump Irrigation in Cystoscopy

Box 1

The physics of flow in a tube.

Flow is defined as the quantity of fluid (including gas) that passes a point per unit time. Flow in a tube is affected

by the following factors:

(i) Pressure difference in the tube

(ii) Length of the tube

(iii) Radius of the tube

(iv) Viscosity of the fluid

These factors have been assimilated into the Hagen-Poiseuille equation:

              Flow(Δ𝑄)=𝜋𝑃𝑟⁴/8𝑙𝜂,

where 𝑃—pressure difference in the tube; 𝑟—radius of the tube; 𝑙—length of the tube; 𝜂—viscosity of the fluid