Résumé:
Nanofluids are considered the working fluids of the future due to their improved thermophysical properties. However, the behavior of nanofluids in terms of improved heat transfer and flow characteristics remains a very interesting topic, whether for their various practical applications in industry or for the fundamental questions it raises.
Within the framework of this thesis, many numerical investigations have been carried out on the problem of convection in the presence of nanofluids in various situations and environments in order to acquire a solid understanding of this new type of working fluid. The first part of the thesis deals with the study of the forced convection of (Al2O3/Water)
nanofluids flow through a three-dimensional 90° elbow using a two-phase model under turbulent conditions. The effects of Reynolds number, nanoparticle volume fraction and nanoparticle diameter were discussed. The second part offers an in-depth analysis of the problem of mixed convection of (Al2O3- Cu/Water) hybrid nanofluids with the presence of a magnetic field for a wide range of parameters in a cavity having two rounded corners. The third part aims to perform an energetic and exergetic analysis of (Fe3O4/Water) nanofluids flow in three different heat sink scenarios using the finite volume approach. The fourth part presents a highly efficient hybrid approach to improve the thermal performance of the cooling system of an electronic component. The proposed research technique consists of incorporating a magnetic nanofluid, a magnetic field inducer and a porous medium into the system. The two-phase model is used in order to increase the accuracy of the results
obtained.
The fifth and final part focuses on the impact of a magnetic source placed in the vicinity of
the heater under mixed convection conditions in a novel cavity having two arc-shaped plates
filled with (Fe3O4/water) magnetic nanofluid.
