# Flow Rate (related to velocity)

## Description

Flow rate is defined to be the volume of fluid passing by some location through an area during a period of time.

The change in volume is the amount that flows after crossing the boundary for some time duration, not simply the initial amount of volume at the boundary minus the final amount at the boundary, since the change in volume flowing through the area would be zero for steady flow.

## Variables

Q | Flow rate (m^{3}/s) |

Δ_{V} | Volume of fluid which passes through the surface (m^{3}) |

Δ_{t} | Elapsed time (s) |