Plumes emission from a fracture on a planetary surface using Smoothed Particle Hydrodynamics: The case of Enceladus

Abstract

The emission of volatiles from the surface and subsurface of planetary bodies can provide fundamental knowledge concerning their formation, evolution, and structure. There are a variety of physical processes that shape the structural, kinematic and thermal behavior of the released material. We simulate Enceladus’ plumes outgassing from a surface fracture, characterizing their dynamical and thermal behavior by introducing an advanced numerical model, that adopts the Smoothed Particle Hydrodynamics (SPH) approach. We target and discuss the challenging implementation of several important microscopic phenomena that can alter the macroscopic properties of the simulated plume. Indeed, we consider the dynamical interaction with solid boundaries, the phase transitions, the solar radiation, the thermal interaction with Enceladus’ surface, the viscous drag coupling and the gravitational attraction. We run simulations with two values of the icy grains size, to explore the role of such parameter in the considered effects. The simulations results are consistent with the expected physical behavior and the observed properties of Enceladus’ plumes. We discuss the role of the processes in shaping the velocity, temperature, and density distributions for the vapor and ice components. We calculate the amount of mass loss from the surface fracture, obtaining values consistent with previous estimates. Similarly occurs for the ice deposition rate near the fracture, over the surface of Enceladus. The good agreement between our results and the current knowledge about Enceladus’ plumes supports the strength of an SPH based approach to study the emission of volatiles from the surface and subsurface of planetary objects. Such a model offers a unique tool in the investigation of the occurring phenomena, as well as for predicting and comparing with observations.