الفهرس 
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Abstract
Hybrid nano fluid is a new class derived from nano fluids that yields better enhancement in heat transfer. Natural convection and heat transfer behavior are numerically investigated for hybrid nanofluids inside a square enclosure. Both vertical sides are insulated, while the lower and upper surfaces are influenced to heat generation and absorption. The enclosure is filled with different types of Hybrid nanofluids along with changeable conditions. This study deals with two types of hybrid nano fluid; the first for Silver Magnesium Oxide Ag-MgO/water hybrid fluid and the second for Copper Aluminum oxide water Al2O3 –Cu hybrid fluid. Each type is studied under assorted parameters as, varying of Nanoparticle concentration (𝜑) for range 0.0% to 2%, while temperature for heat generation and absorption (q) varies from -10 to 10, and Rayleigh number (Ra) varies from 103 ≤Ra ≤106. This investigation is accomplished through a computer program (Fortran/ patankar), that basically depend on the Finite Volume Method. Also, for code verification a good agreement is found for comparing some of these results with the published data. In order to upgrade solution accuracy, the predicted Nusselt number is presented through Artificial Neural network (ANN). In addition, Isocontour maps for Nusselt number have been created at different studied parameter ranges (Ra, and 𝜑). The results in conclusion show improvement in both types of hybrid performance as Nu increases for each case of hybrid but with limits. As, it is revealed that adding hybrid nano particles increases heat transfer enhancement for heat generation (q) from -10 to (q) = 5, while for (q) ˃ 5 there is a reverse effect. In general, Nusselt number is enhanced more by adding hybrid nano particles rather than pure water. As, for using Ag-MgO/water hybrid fluid at Ra=106 the maximum increase in Nu is 11.1% for hybrid concentration with (𝜑) =2% till (q) iii =5. While for Al2O3 –Cu water hybrid with a lower concentration of(𝜑)=0.1% has slight maximum increase in Nu with 2.6% for Ra= 106 till (q) =0.