# Local derivative

From AMS Glossary

## local derivative

The rate of change of a quantity with respect to time at a fixed point of a fluid, ∂

*f*/∂*t*.It is related to the individual derivative where

*df*/*dt*through the expression*f*is a thermodynamic property*f*(*x*,*y*,*z*,*t*) of the fluid,**V**the vector velocity of the fluid, and**∇**the del operator.*See*partial derivative.