Effect of vibrations on pore fluid distribution in porous media - Experimental investigations

Modeling pore fluid distribution in porous media is an essential task in the exploration of plant growth under microgravity. The effects of vehicle vibrations (during launch and post-launch periods) and possible particle separation under zero gravity complicate the modeling of the distribution of water and air in plant growth chambers. In this paper, results from experimental investigations are reported on the distribution of immiscible fluid phases in soils and glass beads under the effects of vibrations. Hexadecane, a petroleum compound immiscible with and lighter than water, is used in the experiments. The higher freezing point of Hexadecane (18 degrees C) allowed the solidification of the entrapped blobs in the presence of water in porous media, so that their size distribution can be obtained. van Genuchten's function, commonly used to express moisture retention curves, is found to be an adequate fit for the blob size distributions. It is concluded that the effect of vibrations is to break up blobs entrapped in porous media at residual saturation and reduce the mean blob size. The pore fluid distributions after vibrations are less uniform than those before vibrations.