Modeling and simulation of near-field enceladus plumes from tiger stripe fractures using a collision-limiter condensation model

The Saturn orbiter, Cassini during its flyby of Saturn's moon, Enceladus in 2005 discov- ered plume of water vapor and ice grains in the south-polar region, primarily originating from four prominent fractures known as tiger stripes. Significant differences between gas and grain velocities suggest that the plume source lies beneath the satellite's surface. The primary work discussed in this paper is to model the subsurface gas and ice grain flow from a source by using a 45 m long subsurface channel. The gas flow inside the channel is continuum and inviscid in nature and is solved using an equilibrium direct simulation Monte Carlo(eDSMC) approach. Since, ice grains are present in small concentration in the plume, it is possible to model the ice grain flow by using the background gas proper- ties. An overlay technique to model the ice grain number density and radius distribution along the channel is also described. The gas and ice grains flows are also modeled for the domain outside the channel. Results for gas and ice grains properties for two dfferent kind of subsurface channel shapes and outside the channel are presented. The gas and ice grain number densities decrease rapidly after the channel's exit suggesting that the flow is free-molecular after some distance from the surface.