Equivalence between simple multilayered and homogeneous laboratory-based rheological models in planetary science

TL;DR

This paper demonstrates that layered planetary models can be effectively approximated by homogeneous models with complex rheology, simplifying tidal response calculations without losing accuracy in dissipation estimates.

Contribution

It introduces methods to match layered and homogeneous models' tidal responses, showing that complex multilayered structures can be replaced by simpler homogeneous models for dissipation analysis.

Findings

Homogeneous models can replicate multilayered tidal responses.

Two methods to determine homogeneous rheology parameters.

Homogeneous models simplify numerical simulations.

Abstract

The goal of this work is to investigate under which circumstances the tidal response of a stratified body can be approximated by that of a homogeneous body. We show that any multilayered planet model can be approximated by a homogeneous body, with the same dissipation of tidal energy as a function of the excitation frequency, as long as the rheology of the homogeneous model is sufficiently complex. Moreover we provide two straightforward methods for finding the parameters of the homogeneous rheology that would exhibit the same tidal response as the layered body. These results highlight the fact that the two models cannot be distinguished from each other only by the measurement of the second degree tidal Love number and quality factor, and that we do not need the complexity of the multilayer planet model in order to estimate its tidal dissipation. The methodology promises a great simplification of the treatment of multilayered bodies in numerical simulations because the treatment of a homogeneous body -- even with a complex rheological model -- can be computationally better handled than that of a multilayered planet.