Frequency spectra of turbulent thermal convection with uniform rotation by Hirdesh K. Pharasi; Krishna Kumar; Jayanta K. Bhattacharjee

The frequency spectra of the entropy and kinetic energy along with the power spectrum of the thermal flux are computed from direct numerical simulations for turbulent Rayleigh-B\'{e}nard convection with uniform rotation about a vertical axis in low-Prandtl-number fluids ($\mathrm{Pr} < 0.6$). Simulations are done for convective Rossby numbers $\mathrm{Ro} \ge 0.2$. The temporal fluctuations of these global quantities show two scaling regimes: (i) $\omega^{-2}$ at higher frequencies for all values of $\mathrm{Ro}$ and (ii) $\omega^{-\gamma_1}$ at intermediate frequencies with $\gamma_1 \approx 4$ for $\mathrm{Ro} > 1$, while $4 < \gamma_1 < 6.6$ for $0.2 \le \mathrm{Ro} < 1$.