10:45 AM - 11:00 AM
[PPS07-06] Development of a poroviscoelastic gravitational theory: Tidal heating in a solid-liquid mixed layer
Keywords:Tides, Solid-liquid mixture, Porous material
Tides are a universal phenomenon that drive the thermal and orbital evolution of planetary bodies. Previously, tidal responses of solid bodies has been modeled assuming that the bodies are made of solid or liquid layers. However, a global solid-liquid mixed layers has been suggested for many planetary bodies. For example, a seawater-filled rocky core of Enceladus and the partially molten layer at the bottom of the lunar mantle, where significant tidal heating is predicted. In addition, thick partial molten layers are expected before the complete solidification of magma oceans in the early stages of solid body formation, and large changes in rotation velocity due to tides are expected in these early stages. In this study, we develop a theory of tidal deformation and tidal heating in the presence of a global solid-liquid mixed layer. Specifically, we integrate the viscoelastic gravitational theory used in conventional tidal studies and the poroelastic theory developed mainly in the field of engineering. As an example, we examine the tidal heating in the rocky core of Enceladus. We find that the motion of seawater in the surfical layer of the rock core can produce a significant amount of heat even without a significant reduction in the viscosity of the solid frame. This is only one example of application; the theory developed in this study should be applicable to various kinds of studies.