SHSLBM Simulation of Hybrid Nanofluid Thermal Convection at High Rayleigh Numbers

A new method called simplified and highly stable lattice Boltzmann method (SHSLBM) was used to simulate the hybrid nanofluid natural convection and heat transfer in a square enclosure with a heating obstacle at high Rayleigh numbers. There are four fins on the heating obstacle to affect the flow pattern and heat transfer performance. SHSLBM is based on the lattice Boltzmann framework. The effects of Rayleigh number (10(6) <= Ra <= 10(9)), nanoparticle volume fraction (0 <= phi <= 0.05) and length of fin (0.1 <= h <= 0.3) on the flow pattern, temperature distribution and heat transfer characteristics were illustrated and analyzed. The benchmark simulation results were performed to the method of validation. Three kinds of flow patterns (steady symmetry, unsteady symmetry and unsteady asymmetry) can be observed at various Rayleigh number. At phi = 0.01, when the Ra increases from 1 x10(6) to 1 x10(9), the transitions of flow regime from steady symmetry state to unsteady asymmetry state occur. The phi and h also affects the flow pattern significantly. At higher phi, the flow inside the enclosure is steadier and the effect of h on the flow pattern varies at different Ra.