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[References: 23 tit.]

In this paper, fluid behavior and the second order statistics of developed turbulent natural convection is numerically predicted by the hybrid lattice Boltzmann method. In order to simulate the high Rayleigh number flow, the high order regularized lattice Boltzmann scheme combined with the finite difference solution of energy equation is used. An in-house code was carefully validated against the reference data computed by different numerical macroscopic and mesoscopic techniques. Simulations were performed for cavity aspect ratio 1 ≤ Ar ≤ 4 and Rayleigh number 1010 ≤ Ra ≤ 1011. It was found that two-dimensional (2D) models overpredicted turbulent statistics in comparison with three-dimensional (3D) models. Moreover, less stratified thermal fields are observed under 2D simulations. However, the mean Nusselt numbers are well agreed both for 2D and 3D models. The proposed hybrid model with uniform grid spacing reproduced integral heat transfer characteristics with acceptable accuracy for engineering applications. In particular, the relative error in the mean Nusselt number is within 5% when comparing the results with conventional fully resolved Navier-Stokes formulation.