The use of a shear thinning polymer as a bubbly magma analogue for scaled laboratory experiments

Jones, Thomas J; Llewellin, Edward W; Mader, Heidy M

Abstract

Analogue materials are commonly used in volcanology to perform scaled laboratory experiments. Analogue experiments inform on fundamental fluid dynamic, structural and mechanical processes that are typically very difficult to observe and quantify directly in the natural volcanic system. Here we investigate the suitability of an aqueous solution of hydroxyethyl cellulose polymer (HEC) for use as a lava/magma analogue, with a particular focus on its rheological behaviour. We characterize a range of physical properties as functions of the concentration and temperature of the solution: density; specific heat capacity; thermal diffusivity; thermal conductivity; surface tension; as well as rheology. HEC has a non-Newtonian, shear-thinning rheology that depends on the concentration and temperature of the solution. We show that the rheology is well described by the Cross model, which was originally developed for polymer solutions, but has also been applied to bubbly magmas. Using this similarity, an approach for scaling analogue experiments that use shear-thinning polymers, like HEC, to bubbly magma is presented. A detailed workflow and a spreadsheet are provided to allow experimentalists to investigate the effects of non-Newtonian behaviour in their existing laboratory set-ups. This contribution will allow for the more complex, but often more realistic case of bubble-bearing magmas to be rigorously studied in experimental volcanology.

Citation

Jones, T. J., Llewellin, E. W., & Mader, H. M. (2020). The use of a shear thinning polymer as a bubbly magma analogue for scaled laboratory experiments. Journal of Volcanology and Geothermal Research, 392, Article 106768. https://doi.org/10.1016/j.jvolgeores.2020.106768

• Journal Article Type: Article
• Acceptance Date: Jan 3, 2020
• Online Publication Date: Jan 11, 2020
• Publication Date: Feb 15, 2020
• Deposit Date: Jan 14, 2020
• Publicly Available Date: Feb 27, 2020
• Journal: Journal of Volcanology and Geothermal Research
• Print ISSN: 0377-0273
• Electronic ISSN: 1872-6097
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 392
• Article Number: 106768
• DOI: https://doi.org/10.1016/j.jvolgeores.2020.106768
• Public URL: https://durham-repository.worktribe.com/output/1279262