Triadic resonances driven by thermal convection in a rotating sphere

Abstract

Abstract

Modulated rotating waves and triadic resonances in spherical fluid systems: The case of magnetized spherical Couette flow

“…In the case of mechanically driven Couette flow in a wide-gap spherical shell, Barik et al (2018) discussed the appearance of a triadic resonance regime in which free inertial modes form a triad with the basic nonaxisymmetric instability. For convection driven fluid flows in full spheres a triadic resonance regime involving inertial waves was found in Lin (2021) linking convection and mechanical drivings in agreement with the theoretical analysis of Zhang and Liao (2017) performed in terms of inertial waves and for either convective or mechanically forced rotating fluids systems.…”

“…While the mechanism proposed here is more general, it is not in contradiction with the interpretation of triadic resonances in terms of inertial waves, as quasiperiodic MRW involving inertial modes can be found as well in spherical (e. g. Garcia, Chambers, and Watts (2019); Lin (2021)) and cylindrical geometry (e. g. Albrecht et al (2018)), and their mathematical description is analogous to that of inertial waves of Barik et al (2018) and the references therein. We demonstrate that resonant interactions prevail on a significant region of the parameter space and even for chaotic flows, generated from further bifurcations of quasiperiodic MRW.…”

“…a) Author to whom correspondence should be addressed: f.garciagonzalez@hzdr. de Recently, triadic resonances were also identified in spherical systems (e. g. Hoff, Harlander, and Triana (2016); Barik et al (2018); Lin (2021)). In the case of mechanically driven Couette flow in a wide-gap spherical shell, Barik et al (2018) discussed the appearance of a triadic resonance regime in which free inertial modes form a triad with the basic nonaxisymmetric instability.…”

Core Eigenmodes and their Impact on the Earth’s Rotation

“…The mantle is thus treated as an electrical insulator, and the magnetic field must satisfy B = ∇ E at the CMB, where E is the exterior potential in the mantle. For simplicity, an electrically insulating ICB is also often considered (e.g., Lin andOgilvie 2018, 2020). However, because such BCs are difficult to enforce in non-spherical geometries, other BCs are sometimes considered (Cébron et al 2012a).…”

“…In addition, resonant couplings may also occur due to the interactions of two inertial modes with another primary inertial mode U 0 (known as triadic interactions), for instance, driven by core convection. Although the typical turnover frequency of the convective eddies is believed to be much smaller than the frequency of the inertial modes, turbulent rotating convection might also sustain higher-frequency flows compatible with inertial waves (Lin 2021). This scenario is still very speculative and deserves further work.…”