Numerical analysis of multiplicity and transition phenomenon in natural convection

This research is devoted to the numerical investigation of the transition and multiplicity phenomena in natural convection. The numerical simulation is performed for a 2-D closed domain using FLUENT, a commercial computational uid dynamics package. In this study, the effects of different parameters such as Rayleigh number (Ra), aspect ratio (AR), and Prandtl number (Pr) are numerically analyzed. The complex phenomenon of onset of instability is studied to find the critical Ra numbers and bifurcation points. In a specific range of critical Ra numbers, transition and multiple results are observed using Rayleigh, boundary condition and pseudo-transient continuation methods. This method uses higher order temperature boundary conditions as an initial value on vertical walls. Multiple steady state results are observed at different Ra numbers. In a range of Ra numbers, the transition and multiple steady state results can completely change the convective ow pattern within the domain.