Permeable or impermeable?


Permeable or impermeable?


Submitted by


Michel Darche
Regis Goiffon

The study of the diffusion of liquids in the soil, also called percolation, allows scientists measuring how water is diffused in the soil, how fast aquifers refill, and to understanding the diffusion of gas, petrol and pollutants in the soil.
It is the English mathematician J. M. Hammersley who, in 1965, highlighted that diffusion and percolation also occur in telecommunication networks, the spreading of epidemics, propagation of fires, and the phase transition from water to ice.

From where comes the difference? Why can water diffuse in certain rocks? 

We can model a porous medium by a regular grid formed with tubes. Tubes are closed at random. If the number of closed tubes is small, then the open tubes form passages through which the water can flow from one side to the other. When increasing the number of closed tubes, a percolation threshold is reached and the medium becomes impermeable.

This module is part of the MPE exhibition. You can rent this module for a lumpsum fee. A detailed manual how to rebuild this module will be shared.