Effect of barodiffusion on the dynamics of gas bubble growth in magmatic melt
A.A. Chernov1,2, M.N. Davydov1,3, S.I. Lezhnin1,2
1Novosibirsk State University, Novosibirsk, Russia
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
3Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia
Keywords: gas bubble, magmatic melt, decompression, barodiffusion, boundary value problem with a moving boundary, numerical simulation
Abstract
The effect of barodiffusion on the dynamics of gas bubble growth in a highly viscous, gas-saturated magmatic melt undergoing rapid decompression is studied. A mathematical model of the process, which represents a joint dynamic and diffusion problem, is proposed. It is shown that as the bubble grows, a diffusive boundary layer is formed around it, leading to the appearance of a large viscosity gradient in the melt and, as a consequence, to a large pressure gradient. A semi-analytical solution of the problem based on the existence of a quasi-stationary state for the bubble growth process is found. It is shown that the effect of barodiffusion is significant at the initial and transient stages of the process. Its influence decreases with time and disappears completely at the stage of diffusion.
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