Nanofluid Heat Transfer in Wavy-Wall Channels with Different Geometries: A Finite-Volume Lattice Boltzmann Study

In this work, we perform an extensive numerical investigation of the heat transfer behavior of nanofluid laminar flows, in wavy-wall channels. The adopted computational approach is based on a finite-volume formulation of the lattice Boltzmann method constructed on a fully-unstructured mesh. We show the validity and effectiveness of this numerical approach to deal with realistic problems involving nanofluid flows, and we employ it to analyze the effects of the wavy-wall channel geometry on the rate of heat transfer, thus providing useful information to the design of efficient heat transfer devices. Results show that an increasing of the wavy surface amplitude has a positive effect on the heat transfer rate, while a phase shift between the wavy walls leads to a decreasing of the mean Nusselt number along the channel. The addition of solid nanoparticles within a base liquid significantly contributes to increase the rate of heat transfer, especially when a relatively high value of nanoparticles volume fraction is employed. The present analysis then suggests that the use of nanofluids within an axis-symmetric configuration of the wavy-wall channel, with high wavy surface amplitude, may represent an optimal solution to enhance the thermal performances of heat transfer devices.