A percolation approach to aerogel gas permeability

We performed a numerical and theoretical study of the critical behaviour of the permeability to gases in aerogels of different densities. In order to compute the critical exponent, it has been necessary to calculate the perco lation critical density for densifying aerogels. As a final result, the per meability critical exponent is found to be different to that of random medi a. The theoretical and numerical results agree very well.