Volcano fluid dynamics & modeling
Explosive eruptions involve high temperature, high velocity flows of gas-particle mixtures. These extreme conditions make it very difficult to obtain detailed, well-controlled measurements of the different types of flows. And, although there is much to learn from detailed studies of pyroclastic deposits, it is usually impossible to exactly determine the conditions that produce their characteristics. In order to continue to advance our understanding of explosive activity it is essential to integrate theoretical and modeling approaches with real-time observations and studies of deposits. Theory and modeling involve the mathematical exploration of the impacts of different conditions and processes on volcanic flows, either through analytical techniques or by computer modeling, and comparison of mathematical models with controlled experiments and observations.
Theoretical studies of volcano fluid dynamics always center on partial differential equations that describe the conservation of mass, momentum, and energy for the fluid or particle-fluid mixture. Much of my modeling work has focused on understanding multiphase processes of gas-particle mixtures in volcanic eruptions. This has included describing the general implications for how volcanic particles may be carried in a pyroclastic surge by turbulence, and the effects of the resulting density gradients (reflecting progressive concentration of relatively dense particles toward the base of a laterally-moving surge) on deposit facies, an extension of sediment transport theory that is more commonly used in surface hydrology. That work was followed by computer modeling that numerically solved the coupled conservation equations for both a carrier gas phase and dispersed particles. The numerical approach allowed my colleagues and I to explore some of the dynamics of collapsing volcanic eruption columns (also referred to as fountains) that produce high-speed pyroclastic flows and surges (see also Pyroclastic deposits). More recently, I have worked with Sebastien Dartevelle to model the time-dependent processes of flow in volcanic conduits and underground tunnels at the proposed Yucca Mountain radioactive waste repository (see Volcanic risk).
My current research interests in the area of volcano fluid dynamics & modeling continue to focus on multiphase processes, particularly on two classes of problems. First is dynamics of conduit flow and eruption columns for basaltic volcanoes, particularly focusing on the causes and consequences of different eruptive styles and sustained basaltic explosive jetting that produces so-called violent Strombolian activity. The second class of problems explores the dynamics of pyroclastic flows, particularly the transition from proximal to medial and distal dynamics, and predicting the effects of pyroclastic flows on human infrastructure (see Volcanic risk). The UB volcano studies group also has a major modeling effort on granular volcanic flows over complex terrain (TITAN2D).