  We analyze the Prandtl number (Pr) dependence of spectra and fluxes of
kinetic energy, as well as the energy injection rates and dissipation rates, of
turbulent thermal convection using numerical data. As expected, for a flow with
$ \mathrm{Pr} \lessapprox 1 $, the inertial-range kinetic energy flux is
constant, and the kinetic energy spectrum is Kolmogorov-like ($ k^{-5/3} $).
More importantly, we show that the amplitudes of the kinetic energy fluxes and
spectra and those of structure functions increase with the decrease of Pr, thus
exhibiting stronger nonlinearity for flows with small Prandtl numbers.
Consistent with these observations, the kinetic energy injection rates and the
dissipation rates too increase with the decrease of Pr. Our results are in
agreement with earlier studies that report the Reynolds number to be a
decreasing function of Prandtl number in turbulent convection. On the other
hand, the tail of the probability distributions of the local heat flux grows
with the increase of Pr, indicating increased fluctuations in the local heat
flux with Pr.
