Darcy's Law - Seepage Velocity:
Seepage Velocity:

Darcy Velocity or Flux:

Flow Gross Cross Sectional Area:

Voids Effective Cross Sectional Area:

where,
v
s = Seepage Velocity,
v = Darcy Velocity or Flux,
A = Flow Gross Cross Sectional Area,
A
v = Voids Effective Cross Sectional Area.