Stefano Ubertini
University of Tuscia, Viterbo, Italy
Abstract:
A nanofluid is a suspension that consists of base liquids and ultrafine nanoparticles which exhibits a great potential in enhancing heat transfer. In this research, a stable cell-centered finite volume formulation of the lattice Boltzmann model is developed to simulate thermal transport of nanofluids. For this purpose, the weighting factors are used as flux correctors to enhance the stability and the double distribution function model is applied to demonstrate the temperature field. The drag and gravitational forces are considered as major external forces and the Brownian and repulsion and attractive potentials are taken into account as major inter-particles forces where the DLVO theory is used to calculate interaction potentials. All these forces make the thermal transport inside the nanofluid improved. The stability parameters of nanofluid are discussed a modified version of HC model is derived to calculate the effective thermal conductivity. The scheme is established to s!
imulate thermo-hydrodynamic characteristics of various nanofluids for plane duct and backward facing step flows. Results show that within vortex zones of backward facing flow, nano-particles with low thermal conductivity lead to a more pronounced enhancement of the Nusselt number. On the other hand, high-conductivity nano-particles prove more effective outside the recirculation zone. These findings provide useful information for the optimization of heat transport phenomena in industrial interest. In addition, the use of a non-uniform grid is found to provide nearly an order of magnitude of computational saving compared to the corresponding scheme on a Cartesian grid.