Rotating salt-fingering convection in the limit of small diffusivity ratio and large density ratio

This work theoretically and numerically studies the rotating salt-fingering convection using an asymptotically derived reduced model valid in the limit of small diffusivity and large density ratios, where the strength of convection and rotation are captured by Ra, the ratio of Rayleigh numbers of the destabilizing and stabilizing buoyancy forces, and the Taylor number Ta, respectively. Their relative importance is captured by a single parameter G=(Ra-1)^1/2/Ta with critical value G_c=1 separating strongly (G<G_c) and weakly (G>G_c) rotating regimes, which are best distinguished when the rotation vector is at an angle to the local vertical gravity with broken left-right symmetry. In the strongly rotating regime the saturated states are characterized by layered structures and the magnitudes of domain-averaged salinity flux, kinetic and salinity potential energies increase linearly as Ta increases, which differs from that in the weak rotation regime and is explained based on the rotation-confined region of linearly unstable modes and an assumption of self-similar energy spectra. Two-peak shapes are observed for both kinetic and potential energy spectra, and the power-law spectra between the two peaks are explained with exponents calculated.