Thermal-Wave Spectroscopy: A New Probe of Porous Media

A nondestructive type of measurement, thermal-wave spectroscopy, is proposed to determine the porosity, the distribution of length scales, and the dynamically connected pore-size parameter, $\Lambda$, of an electrically insulating porous medium. The idea is to heat selectively with a modulated source the water-saturated porous medium and to study the resulting temperature distribution, e.g., by monitoring the electrical conductivity. Exact expressions for the low- and high-frequency behavior are derived.