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

• Published in: Journal of thermal analysis and calorimetry 2021, Vol.143 (1), p.751-765
• Main Authors: Benos, Lefteris Th, Polychronopoulos, Nickolas D., Mahabaleshwar, Ulavathi S., Lorenzini, Giulio, Sarris, Ioannis E.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Analysis; Analytical Chemistry; Asymptotic methods; Bioengineering; Chemistry; Chemistry and Materials Science; Computational fluid dynamics; Computing time; Convection heating; Deterioration; Electric properties; Enclosures; First principles; Fluid flow; Free convection; Inorganic Chemistry; Investigations; Magnetic fields; Magnetic flux; Magnetic permeability; Magnetohydrodynamics; Measurement Science and Instrumentation; Nanofluids; Nanoparticles; Numerical analysis; Permeability; Physical Chemistry; Polymer Sciences; Porous media; Thermal conductivity; Titanium dioxide
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-019-09165-w

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 TiO 2 ) 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.