# Discharge or Flow Rate

**Discharge (also called flow rate)**

The amount of fluid passing a section of a stream in unit time is called the discharge. If *v* is the mean velocity and *A* is the cross sectional area, the discharge *Q* is defined by *Q* = *Av* which is known as volume flow rate. Discharge is also expressed as mass flow rate and weight flow rate.

Mass flow rate, $M = \rho Q$

Weight flow rate, $W = \gamma Q$