(311c) Links Between Synthetic Membrane Formation and Geologic Ice Lens Formation

There is an intriguing similarity between the physics that occurs during some synthetic membrane formation processes, and the geological formation of discrete lenses of ices during freezing of a wet, natural soil. Relatively weak but long-range inter-molecular forces can lead to different structures depending on the chemical and/or thermal gradients present during formation. Because these two processes usually occur in widely different environments, laboratories and chemical process facilities versus alpine mountain ranges and arctic tundra, the connection remained elusive for quite some time. Professor William Krantz, whose wide-ranging interests reached into both of these areas, was one of the pioneers who helped recognize this similarity, and helped develop some important analytic tools for describing the ice-lens formation process. The more comprehensive descriptions of this "separation" process, soil particles from pure ice, involve processes that occur on size scales spanning 7 orders of magnitude, from nanometer to centimeter. Effective scaling of the equations that describe these processes allows for some strikingly compact yet accurate predictive models. The continuing advancements in numerical computing power has recently allowed for further exploration of the lens-formation process under a wider range of circumstances. These simulations have not only confirmed many of the assumptions underlying the analytic scaling arguments, but also allowed for exploration of higher-dimensional (2D and 3D) systems. The perhaps even more interesting occurrence of a particular type of arctic patterned ground emerges naturally from some of these numerical simulations, and may also have an analog in synthetic membrane formation.