Unsteady Three-Dimensional Behavior of Natural Convection in Horizontal Annulus, (III)

Validity of Direct Numerical Simulation of Turbulent Natural Convection

Abstract

Direct numerical simulation using the three-dimensional and time-dependent finite difference scheme which have been reported in the previous paper is performed for turbulent natural convection in a horizontal concentric annulus. Numerical results are obtained for the Rayleigh number based on the gap width from 1.0×10⁶ to 1.72×10⁷. To verify the validity of the present scheme, numerical results dealt with statistically are compared with other experimental data and numerical solutions and the effect of grid size on spatial resolution capability is investigated. It is shown that time-averaged quantities deduced from appropriate spatial resolution are in good agreement with experimental results, whereas turbulence quantities are excessively estimated when spatial resolution is insufficient.