Definitions for "Flux Density"
The number of flux lines per unit of area, measured at right angles to the direction of the flux. It is the measure of magnetic field strength.
The flux density of water passing through a soil is the volume of water passing through the soil per unit cross-sectional area (perpendicular to the flow) per unit time. It has units of length per unit time such as mm/sec, mm/hour, or inches/ day. Many times flux and flux density are used interchangeably.
Flux across a unit cross-sectional area.