Dane Sterbentz, University of California, Davis
Dynamic-compression experiments use shock-wave and ramp-wave compression to probe the behavior of materials under extreme pressures. Due to their rapid nature, these types of experiments present a number of challenges for studying nonequilibrium material behavior, such as first-order phase transitions. This work investigates the submicrosecond phase transition kinetics of materials in dynamic-compression experiments using computational modeling and methods based in classical nucleation theory (CNT). The transition of liquid water to the ice VII phase (a high-pressure solid water polymorph) is the focus of this research. Several aspects of the process of modeling these types of dynamic-compression experiments and the kinetics of the phase transitions that occur are discussed. This includes an investigation of transient-phase transition kinetics and the compression-rate dependence of the phase transition. A novel method for determining the drive pressure in ramp-wave compression experiments using a heuristic optimization algorithm also is discussed. This drive pressure is necessary for performing multiscale simulations of ramp-wave compression experiments that account for both the phase transition kinetics and hydrodynamics of the compressed experimental setup. Lastly, a multilayer model of the solid-liquid interface of developing ice VII clusters is investigated and applied to our CNT-based kinetics simulations to better characterize the energy barrier to nucleation.
Abstract Author(s): Dane M. Sterbentz, Philip C. Myint, Jean-Pierre Delplanque, Jonathan L. Belof