Nanofluid flow and heat transfer in an asymmetric porous channel with expanding or contracting wall

In this study, the least square method (LSM) and the Galerkin method (GM) are used to simulate flow and heat transfer of nanofluid flow between two parallel plates. One of the plates is externally heated, and the other plate, in which coolant fluid is injected through it, expands or contracts with time. The fluid in the channel is water containing different nanoparticles (Cu, Ag and Al2O3). The effective thermal conductivity and viscosity of the nanofluid are calculated by the Maxwell–Garnetts (MG) and Brinkman models, respectively. The effects of the nanoparticle volume fraction, Reynolds number, expansion ratio and power law index on flow and heat transfer are investigated. The results show that the Nusselt number increases with an increase of the nanoparticle volume fraction and Reynolds number. Also it can be found that in order to reach the maximum Nusselt number, copper should be used as a nanoparticle.