Formula
![Reynolds number for porous media formula](http://www.wikicalculator.com/formula_image/Reynolds-number-for-porous-media-398.png)
Re
Reynolds number for porous media flow
rho
density of the fluid
v
mean velocity of the object relative to the fluid
L
linear dimension (travelled length of the fluid; hydraulic diameter when dealing with river systems)
mu
the dynamic viscosity of the fluid