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).