Llewellin, E. W. and Manga, M. (2005) Bubble suspension rheology and implications for conduit flow. Journal of Volcanology and Geothermal Research, 143. pp. 205-217. DOI https://doi.org/10.1016/j.jvolgeores.2004.09.018
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Abstract
Bubbles are ubiquitous in magma during eruption and influence the rheology of the suspension. Despite this, bubblesuspension rheology is routinely ignored in conduit-flow and eruption models, potentially impairing accuracy and resulting in the loss of important phenomenological richness. The omission is due, in part, to a historical confusion in the literature concerning the effect of bubbles on the rheology of a liquid. This confusion has now been largely resolved and recently published studies have identified two viscous regimes: in regime 1, the viscosity of the two-phase (magma–gas) suspension increases as gas volume fraction / increases; in regime 2, the viscosity of the suspension decreases as / increases. The viscous regime for a deforming bubble suspension can be determined by calculating two dimensionless numbers, the capillary number Ca and the dynamic capillary number Cd. We provide a didactic explanation of how to include the effect of bubble-suspension rheology in continuum, conduit-flow models. Bubble-suspension rheology is reviewed and a practical rheological model is presented, followed by an algorithmic, step-by-step guide to including the rheological model in conduit-flow models. Preliminary results from conduit-flow models which have implemented the model presented are discussed and it is concluded that the effect of bubbles on magma rheology may be important in nature and results in a decrease of at least 800 m in calculated agmentation-depth and an increase of between 40% and 250% in calculated eruption-rate compared with the assumption of Newtonian rheology. D 2005 Elsevier B.V. All rights reserved.
Item Type: | Article |
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Uncontrolled Keywords: | NIL AREP IA50 2005 P BPI |
Subjects: | 05 - Petrology - Igneous, Metamorphic and Volcanic Studies |
Divisions: | 05 - Petrology - Igneous, Metamorphic and Volcanic Studies |
Journal or Publication Title: | Journal of Volcanology and Geothermal Research |
Volume: | 143 |
Page Range: | pp. 205-217 |
Identification Number: | https://doi.org/10.1016/j.jvolgeores.2004.09.018 |
Depositing User: | Sarah Humbert |
Date Deposited: | 18 Feb 2011 17:26 |
Last Modified: | 23 Jul 2013 09:59 |
URI: | http://eprints.esc.cam.ac.uk/id/eprint/1728 |
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