Multiphase Flow Modeling And Simulation Of Explosive Volcanic Eruptions

We have adapted computer codes that provide such solutions to study explosive volcanic phenomena. These fully nonlinear conservation equations are cast in two-dimensional cylindrical coordinates, which with closure equations comprise 16 equations with 16 unknown variables. Solutions for several hundred seconds of simulated eruption time require two to three hours of a Cray-1 computer time. Over 100 simulations have been run to simulate the physics of highly unsteady blasts, sustained and steady Plinian eruptions, fountaining, column eruptions, and multiphase flow of magma in lithospheric conduits. The unsteady-flow calculations show resemblance to shock-tube physics with propagation of shock waves into the atmosphere and rarefaction waves down the volcanic conduit. Steady-flow eruption simulations demonstrate the importance of supersonic flow and over pressure of erupted jets of tephra and gases in determining whether the jet will buoyantly rise or collapse back to the earth as a fountain. Flow conditions within conduits rising through the lithosphere determine eruptive conditions of overpressure, velocity, bulk density, and vent size. Such conditions within conduit systems are thought to be linked to low-frequency, sustained seismicity known as volcanic tremor. These calculations demonstrate the validity of some analytical eruption calculations under limited conditions. 31 refs., 10 figs., 1 tab.

The Physics of Explosive Volcanic Eruptions includes seven review papers that outline our current understanding of several aspects of the physical processes affecting magma during volcanic eruptions. An introductory chapter highlights research areas where our understanding is incomplete, or even completely lacking, and where work needs advancing if our knowledge of volcanic processes is to be substantially improved. The book covers topics on the physical properties of silicic magma, vesiculation processes, conduit flow and fragmentation, gas loss from magmas during eruption, models of volcanic eruption columns, tephra dispersal and pyroclastic density currents.

A summary of insights into key aspects of explosive volcanic eruptions, arranged into chapters in order of the processes involved, from the hot magma releasing gases as it rises through the Earth's crust to the final deposition of materials upon the Earth's surface.

An advanced textbook and reference resource examining the physics of volcanic behavior and the state of the art in modeling volcanic processes.

Because of the importance of multiphase flows in a wide variety of industries, including power, petroleum, and numerous processing industries, an understanding of the behavior and underlying theoretical concepts of these systems is critical. Contributed by a team of prominent experts led by a specialist with more than thirty years of experience, the Multiphase Flow Handbook provides such an understanding, and much more. It covers all aspects of multiphase flows, from fundamentals to numerical methods and instrumentation. The book begins with an introduction to the fundamentals of particle/fluid/bubble interactions followed by gas/liquid flows and methods for calculating system parameters. It includes up-to-date information on practical industrial applications such as boiling and condensation, fluidized beds, aerosols, separation systems, pollution control, granular and porous media flow, pneumatic and slurry transport, and sprays. Coverage then turns to the most recent information on particle/droplet-fluid interactions, with a chapter devoted to microgravity and microscale flows and another on basic multiphase interactions. Rounding out the presentation, the authors discuss numerical methods, state-of-the art instrumentation, and advanced experimental techniques. Supplying up-to-date, authoritative information on all aspects of multiphase flows along with numerous problems and examples, the Multiphase Flow Handbook is the most complete reference available for understanding the flow of multiphase mixtures.

Understanding the physical behavior of volcanoes is key to mitigating the hazards active volcanoes pose to the ever-increasing populations living nearby. The processes involved in volcanic eruptions are driven by a series of interlinked physical phenomena, and to fully understand these, volcanologists must employ various physics subdisciplines. This book provides the first advanced-level, one-stop resource examining the physics of volcanic behavior and reviewing the state-of-the-art in modeling volcanic processes. Each chapter begins by explaining simple modeling formulations and progresses to present cutting-edge research illustrated by case studies. Individual chapters cover subsurface magmatic processes through to eruption in various environments and conclude with the application of modeling to understanding the other volcanic planets of our Solar System. Providing an accessible and practical text for graduate students of physical volcanology, this book is also an important resource for researchers and professionals in the fields of volcanology, geophysics, geochemistry, petrology and natural hazards.

Explosive volcanic eruptions are complex systems that can generate a variety of hazardous phenomena, for example, the injection of volcanic ash into the atmosphere or the generation of pyroclastic density currents. Explosive eruptions occur when a turbulent multiphase mixture, initially predominantly composedf of fragmented magma and gases, is injected from the volcanic vent into the atmosphere. For plume modelling purposes, a specific volcanic eruption scenario based on eruption type, style or magnitude is strictly linked to magmatic and vent conditions, despite the subsequent evolution of the plume being influenced by the interaction of the erupted material with the atmosphere. In this chapter, different methodologies for investigating eruptive source conditions and the subsequent evolution of the eruptive plumes are presented. The methodologies range from observational techniques to large-scale experiments and numerical models. Results confirm the relevance of measuring and observing source conditions, as such studies can improve predictions of the hazards of eruptive columns. The results also demonstrate the need for fundamental future research specifically tailored to answer some of the still open questions: the effect of unsteady flow conditions at the source on the eruptive column dynamics and the interaction between a convective plume and wind.