On the damping of tidally driven oscillations

TL;DR

This paper investigates the damping mechanisms of tidally driven oscillations in celestial bodies, proposing a new approach that accounts for mode coupling without needing damping rates, improving predictions of orbital evolution.

Contribution

It introduces an alternative method for modeling damping of tidally driven oscillations that incorporates mode coupling using only eigenfunctions and eigenfrequencies.

Findings

Mode coupling significantly affects tidal dissipation predictions.

The proposed method improves accuracy over independent damping rate calculations.

Applicable to both non-rotating and rotating bodies.

Abstract

Expansions in the oscillation modes of tidally perturbed bodies provide a useful framework for representing tidally induced flows. However, recent work has demonstrated that such expansions produce inaccurate predictions for secular orbital evolution when mode damping rates are computed independently. We explore the coupling of collectively driven modes by frictional and viscous dissipation, in tidally perturbed bodies that are both non-rotating and rigidly rotating. This exploration leads us to propose an alternative approach to treating the damping of tidally driven oscillations that accounts for dissipative mode coupling, but which does not require any information beyond the eigenfunctions and eigenfrequencies of adiabatic modes.