ABSTRACT
Over the past two decades, nanofluids have emerged as a promising technology for the enhancement of the intrinsic thermophysical properties of conventional heat transfer fluids. This innovative technology caught the attention of the heat transfer community as a way to improve the poor heat transfer properties of many fluids used in heat transfer applications, for example, water and oils. Many researchers in the community investigated the merits of dispersing nanometer-sized particles into base fluids to enhance heat transfer in mixed convection settings. Abu-Nada and Chamkha [1] conducted a computational study on mixed convection in a lid-driven cavity filled with a nanofluid (water + Al2O3). Significant heat transfer enhancement was observed in the study due to the addition of nanoparticles. In another investigation, Chamkha and Abu-Nada [2] tested the effect of using different viscosity models on mixed convection heat transfer in single-and double-lid-driven square cavities filled with the same nanofluid. They found that for small Richardson numbers, the Pak and Cho model gives a reduction in the average Nusselt number for the single-lid-driven cavities compared with other viscosity models. Tiwari and Das [3] studied heat transfer augmentation in a two-sided nanofluid-filled, lid-driven cavity. They solved twodimensional, single-phase equations using the finite volume method and observed the need for a higher Richardson number to move nanofluids at higher solid volume fraction as a result of the increased viscosity of nanofluids compared to base fluids. Afrouzi and Farhadi [4] investigated mixed convection in a lid-driven cavity filled with Cu-water nanofluid using a cubical heater located inside the cavity in different positions. They found an enhancement in heat transfer with the increase of nanoparticle volume fraction. Ahmad and Pop [5] studied mixed convection in a vertical boundary layer in a porous medium saturated with nanofluids. They used a two-dimensional similarity solution. Billah et al. [6] conducted a computational study for mixed convection in a lid-driven, inclined, triangular enclosure filled with Cu-water nanofluid. They found that the inclination angle affects the dynamics of the flow more than it affects the thermal field. Arani et al. [7] did research on the effects of inclination angle in a partially heated enclosure filled with nanofluid on mixed convection heat transfer and found that the heat transfer is enhanced with increasing the inclination angle. Esfe et al. [8] studied mixed convection in a lid-driven cavity with an obstacle by investigating nanofluid variable properties. They observed that the heat transfer rate is increased with increasing the geometric parameters of the obstacle block and
increasing the nanoparticle volume fraction. A study of using different nanofluids on lid-driven porous cavities in mixed convection was performed by Mittal et al. [9]. In addition to one-phase analysis of nanofluids, two-phase mixture model was used in studying mixed convection in nanofluid [10]. The main finding is that increasing the volume fraction of nanoparticles enhances the convective heat transfer coefficient and consequently the Nusselt number, although it has a negligible effect on the wall shear stress and the corresponding skin friction factor. Sebdani et al. [11] studied the mixed convection heat transfer in a two-sided, lid-driven, nanofluid-filled cavity with partial heater. Both the location of the heat source and the nanoparticle volume fraction were found to affect the heat transfer. Arefmanesh and Mahmoodi [12] investigated the effects of uncertainties in different viscosity models for Al2O3 nanofluid on mixed convection. They reported a difference between Maiga and Brinkman models. Izadi et al. [13] investigated the effect of Richardson number ratio at the walls on the laminar mixed convection of a nanofluid flowing in an annulus under uniform heating condition. They found that heat transfer coefficient increased with increasing Al2O3 nanoparticle volume fraction. Kalteh et al. [14] focused, in their numerical study, on mixed convection in a lid-driven cavity filled with water-based nanofluid and in the presence of a triangular heat source. The results support the claim that dispersing nanoparticles in pure fluids leads to a significant heat transfer enhancement. Mixed convection in nanofluid-filled triangular enclosure was investigated by Ghasemi and Aminossadati [15] using finite volume method and Brinkman model and found that Al2O3 nanoparticles enhance the heat transfer. Nemati et al. [16] applied the lattice Boltzmann method to simulate the nanofluid mixed convection heat transfer in a lid-driven cavity and showed a good agreement with the results reported in literature. They indicated that the effects of solid volume fraction grow stronger sequentially for Al2O3, CuO, and Cu. Alinia et al. [17] used a two-phase mixture model to simulate mixed convection in nanofluid-filled lid-driven enclosure. Their results, also, suggest that the addition of nanoparticles enhances the heat transfer. Gümgüm and Sezgin [18] applied dual reciprocity boundary element method (DRBEM) solution technique to solve mixed convection of nanofluids in enclosures with moving walls. They disclosed that the average Nusselt number increased with increasing volume fraction of nanoparticles and decreased with increasing Ri number. Other studies can be found in references [19-21].
