An expansion–coalescence model to track gas bubble populations in magmas

Abstract We propose a kinetic model that statistically describes the growth by decompression, exsolution and coalescence of a polydisperse population of gas bubbles in a silicate melt. The model is homogeneous in space and its main variable is a distribution function representing the probability to find a bubble of volume v and mass m at time t. The volume and mass growth rates are described by a simplification of the classical monodisperse bubble growth model. This simplification, which shortens computational time, removes the coupling between mass evolution and an advection–diffusion equation describing the behavior of the volatile concentration in the melt. We formulate three coalescence…