Determine the effect of molecular viscosity on inertial-wave evolution

Determine whether the conclusion that coupled orbital and structural evolution is insensitive to the Ekman number remains valid when inertial-wave damping is modeled using molecular viscosity with Ekman number approximately 10^-17.

Background

The calculations explore Ekman numbers down to 10-10 and find that the principal resonant features and qualitative orbital evolution are not sensitive to the adopted viscosity in this range. However, the molecular viscosity inferred from the structure models corresponds to much smaller Ekman numbers, approximately 10-12–10-17. The authors therefore leave unresolved whether the same qualitative behavior persists in the molecular-viscosity regime.

References

Future work should confirm whether this conclusion holds if only molecular viscosity is used ($Ek{\sim}10{-17}$).

— The Neptunian Final Parsec Problem: How Inertial Waves Enable Neptunes and Gas Giants to Survive Tidal Migration  (2610.12968 - Hallatt et al., 9 Oct 2026) in Section 2.2.3, subsection “Viscosity”

Future work should address whether non-convective layers would qualitatively change the runaway inflation mechanism we have described.

— The Neptunian Final Parsec Problem: How Inertial Waves Enable Neptunes and Gas Giants to Survive Tidal Migration  (2610.12968 - Hallatt et al., 9 Oct 2026) in Section 6.3, subsection “Future Work: non-convective interiors”