Rayleigh-Bénard cell formation of green synthesized nano-particles of silver and selenium

In the present study Rayleigh-Bénard convection has been studied in metallic and non metallic nanofluids, prepared from green synthesized silver and selenium nano-particles (NPs) using Azadirachta indica plant (Neem) as an effective bio-product. It is observed that at room temperature, low concentrations of leaf extract of Neem is sufficient to biosynthesize silver NPs in lab from silver nitrate solution and selenium NPs from sodium selenite, which is indicated by the change in color of the solution. The characterization of the obtained nanoparticles further confirms the green synthesis of the nanoparticles. The formation of Bénard cells is delayed in silver and selenium nano-fluids in comparison to simple water proving that the presence of nano-particles in base fluid increases the heat capacity of fluid. These results are validated by mathematically solving the partial differential equations based on conservation laws to get the analytic expression for thermal Rayleigh number which indicates the presence of convection process.