  In this paper, we analyze the scaling of velocity structure functions of
turbulent thermal convection. Using high-resolution numerical simulations, we
show that the structure functions scale similar to those of hydrodynamic
turbulence, with the scaling exponents in agreement with She and Leveque's
predictions [Phys. Rev. Lett. 72, 336-339 (1994)]. The probability distribution
functions of velocity increments are non-Gaussian with wide tails in the
dissipative scales and become close to Gaussian in the inertial range. The
tails of the probability distribution follow a stretched exponential. We also
show that in thermal convection, the energy flux in the inertial range is less
than the viscous dissipation rate. This is unlike in hydrodynamic turbulence
where the energy flux and the dissipation rate are equal.
