Volumetric flux

In fluid dynamics, the volumetric flux is the rate of volume flow across a unit area (m3·s−1·m−2). 
Volumetric flux = liters/(second*area). The density of a particular property in a fluid's volume, multiplied with the volumetric flux of the fluid, thus defines the advective flux of that property. The volumetric flux through a porous medium is often modelled using Darcy's law.
Volumetric flux is not to be confused with volumetric flow rate, which is the volume of fluid that passes through a "given" surface per unit of time (as opposed to a "unit" surface).