# Tortuosity

Written by Jerry Ratzlaff on . Posted in Geotechnical Engineering

Tortuosity, abbreviated as $$\tau$$ (Greek symbol tau), a dimensionless number, is the dispersion of fluid flow in porous media.  In a packed soil there is a decrease in a solutions rate of diffusion due to the presence of wandering paths within the pores of a packed soil.  The presence of such paths result in a slower rate of travel for the solution through the medium.

## Tortuosity formula

 $$\large{ \tau = \frac{ l }{ C } }$$

### Where:

 Units English Metric $$\large{ \tau }$$  (Greek symbol tau) = tortuosity $$\large{dimensionless}$$ $$\large{ l }$$ = length of the curve $$\large{in}$$ $$\large{mm}$$ $$\large{ C }$$ = distance between the ends of the curve $$\large{in}$$ $$\large{mm}$$