Abstract/Summary

We have established previously, that the spreading of liquids in granular porous media at low levels of saturation, typically less than 10% of the available void space, has very distinctive features in comparison to that at higher saturation levels. In particular, we showed that the spreading is controlled by a special type of diffusional process, that its physics can be captured by an equation of the super-fast diffusion class, and these findings were supported by first-of-a-kind experiments. In this paper, we take these findings to the next level including deeper examination and exposition of the theory, an expanded set of experiments to address scaling properties, and systematic evaluations of the predictive performance against these experimental data, keeping in mind also potential practical applications.