Unsteady natural convection of nanofluids in an enclosure having finite thickness walls

Numerical simulation of conjugate natural convection in an enclosure filled with Al ₂O ₃/water nanofluid has been carried out. The Navier-Stokes and energy equations in dimensionless variables such as "stream function-vorticity-temperature" have been solved numerically. Special attention was paid to the effects of the Rayleigh number Ra _f = 10 ⁴, 10 ⁵, and 10 ⁶, dimensionless time 0 < τ < 1000, solid wall thickness, and the thermal conductivity ratio on both local and integral parameters. Detailed results including streamlines, temperature, and vorticity profiles in terms of the key parameters have been obtained. Features of the thermo-hydrodynamic fields due to the presence of the nanoparticles have been determined.