# User:Hoogs/Sandpit

From OpenFOAMWiki

Define the *convective*, *total* or *material* *material* derivative operator as

This relates the rate of change of a quantity within an infinitesimal control fluid volume that we would witness if we were riding with it along a streamline (Lagrangian viewpoint), to the rate of change of the quantity that a stationary observer would witness from their vantage point on the streamline (Eulerian viewpoint).