No abstract

The present study aims to identify heat transfer and flow characteristic due to buoyancy forces in a heated enclosure using nanofluid and their behaviors under natural convective heat transfer condition. In the present work nanofluids with water based containing Al 2 O 3 nanoparticle numerically investigated. Numerical works are done on the use of the stable nanofluids under natural convective heat transfer conditions. Process of heating is done in two different ways: in first process the heater mounted to the down wall and in second way it mounted to the left vertical wall with a finite length, also heated and cooled walls keep in a constant temperature. Our numerical simulation has been undertaken incorporating a homogenous solid-liquid mixture. In particular this study deals with Al 2 O 3 nanofluids with Newtonian behavior. Simulation have been carried out in the ranges Ra=10 3-10 6. Our volumetric fraction of nanoparticles was 1.3%. It was shown the Nusselt-Rayleigh number relation and then nanofluid Nu-Ra number diagrams based on found is plotted. Results showed an increasing in Nusselt-Rayleigh number at nanofluids diagrams as compared to Nusselt-Rayleigh relations of pure water. Increase in the average Nusselt number plays a significant role in heat transfer applications. Due to our numerical investigations vertical cavities with nanofluid were better than horizontal cavities. Also the cavities, which we used nanofluid, had better efficiency in natural convection numerical modeling for both horizontal and vertical fluid layer.

In the present research, the behavior of a Newtonian nanofluid (water-Al 2 O 3 ) in a mixture phase model approach is numerically examined. The process of heating is done in two different ways. Deterioration was found in the mean Nusselt number of a nanofluid in the mixture-phase model approach when compared to the mean Nusselt number of pure water. However, in the single-phase model there was an increase in the Nusselt number when compared to the Nusselt number of pure water.

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