Interfacial Water: Unexplained Phenomena: Fid-Bau Portal

Interfacial Water: Unexplained Phenomena

Musa, S. / Florea, D. / van Loon, S. / Wyss, H. / Huyghe, J. M.

The common understanding in up-scaling of porous media mechanics is that pore scale phenomena are well understood. Navier-Stokes, Poiseuille's law, double-layer theory, thermal convection, all are classical theories coming to our rescue to describe the pore scale events in porous media in a strictly quantitative manner. So, most researchers do not feel the need to physically look at what is really happening. In this work we study a number of poorly understood phenomena that take place at that pore scale. These phenomena include formation of hundreds of micrometers wide exclusion zones next to hydrophilic surfaces, formation of colloidal crystals, micro-convective transport and unexpected pH and electric potential gradients across the exclusion zone. Investigating these phenomena is of great benefit for our understanding of porous media and could spark a wide range of applications in different fields. Until now, there is no comprehensive understanding of why these phenomena occur. There are several possible root causes for the formation of the exclusion zone being investigated. These include formation of liquid crystals of water molecules in the exclusion zone and Frohlich-like coherent oscillations. To develop the understanding about these phenomena, we have conducted experiments where we have used a variety of techniques to measure a number of parameters such as flow velocity and viscosity. These techniques include optical microscopy, optical tweezers, multi-particle tracking and interferometry. Examples of the results of these experiments are shown.