Modeling of a gas slug rising in a cylindrical duct and possible applications to volcanic scenarios (Q2039131)

Summary: The paper deals with the mathematical modelling of a gas slug rising in a cylindrical duct filled with an incompressible liquid. This research is motivated by a phenomenon commonly observed during Strombolian eruptions at basaltic volcanoes, that is, mildly explosive events driven by a large bubble of magmatic gas (a slug) rising up the conduit and bursting at the surface. The model is compared with the laboratory experiments described in [\textit{M. R. James} et al., ``Modelling the rapid near-surface expansion of gas slugs in low-viscosity magmas'', Geol. Soc., Spec. Publ. (London) 307, 147--167 (2008; \url{doi:10.1144/SP307.9})] and we prove that the constancy of the slug ascent velocity observed in these experiments is fully justifiable. The model is developed both in the case of a Newtonian fluid and in the case of a non-Newtonian power law fluid, more suitable for magmas, and applied to a volcanic scenario.