# Flow velocity

In continuum mechanics the **flow velocity** in fluid dynamics, also **macroscopic velocity**[1][2] in statistical mechanics, or **drift velocity** in electromagnetism, is a vector field used to mathematically describe the motion of a continuum. The length of the flow velocity vector is the **flow speed** and is a scalar.
It is also called **velocity field**; when evaluated along a line, it is called a **velocity profile** (as in, e.g., law of the wall).