Thermal and flow investigation of MHD natural convection in a nanofluid-saturated porous enclosure: an asymptotic analysis

In the present investigation, asymptotic solutions are obtained regarding the laminar natural convection of a nanofluid in a porous enclosure subject to internal heating and magnetic field, which appears in a plethora of industrial and bioengineering applications. The complicated nature of the nanofluids along with the computational time needed for the magnetohydrodynamic numerical simulations makes this problem too difficult to face with. Hence, the innovation of this study relies on providing a first-principles approach that includes three kinds of widely utilized nanoparticles (Cu, Al(2)O(3)and TiO2) dispersed in aqueous suspension by incorporating a unified way for describing the nanofluid thermal conductivity and viscosity. In addition, the effect of the magnetic field, internal heating, porous medium permeability as well as nanoparticle size and volume fraction is examined via the derived analytical relationships. In brief, the current study suggests that the increase in the magnetic field intensity and the decrease in the medium permeability tend to suppress the nanofluid flow, thus resulting in deterioration of the heat transfer. This deterioration also occurs when the nanofluid becomes denser and the nanoparticles enlarge. Conversely, increasing the internal heating reinforces the convective currents in favor of cooling process. Finally, the present asymptotic solutions are expected to be very useful in various scientific fields given the rapidly growing interest in nanofluids.

Automated summary

The present study obtained asymptotic solutions regarding the laminar natural convection of a nanofluid in a porous enclosure subject to internal heating and magnetic field, which is widely applied in industrial and bioengineering applications. The innovation of this study lies in providing a first-principles approach for describing the thermal conductivity and viscosity of nanofluids with three kinds of nanoparticles dispersed in aqueous suspension, and examining the effects of various factors on nanofluid flow and heat transfer. The study suggests that an increase in magnetic field intensity tends to suppress nanofluid flow, while increasing internal heating reinforces convective currents in favor of cooling process.