# Volumetric flow rate (parallel to the unit normal)

## Description

volumetric flow rate, (also known as volume flow rate, rate of fluid flow or volume velocity) is the volume of fluid which passes per unit time. The only volume flowing through the cross-section is the amount normal to the area; i.e., parallel to the unit normal.

Related formulas## Variables

Q | The volume of fluid which passes through the surface (m^{3}/s) |

v | The flow velocity of the substance elements (m/s) |

A | The cross-section area (m^{2}) |

θ | The angle between the unit normal and the velocity vector of the substance elements (radians) |