Natural Convection and Entropy Generation in a Nanofluid-Filled Semi-Circular Enclosure with Heat Flux Source

The effect of presence of nanoparticles on natural convection and entropy generation in a semi-circular enclosure with present heat flux is investigated numerically in the present work. The enclosure is filled with nanofluids (Cu-water). The heat flux is supplied partly in the center of the base wall, and the other parts of base wall of the enclosure are assumed adiabatic. The center of the circular arc (-45°≤γ≤ + 45°) is assumed at constant cold temperature and the other parts of the circular arc are adiabatic. Finite element method based on the variational formulation is employed to solve momentum and energy as well as post-processing streamfunctions. The results are based on visualization of isotherms, streamfunction and entropy generation. Comparison with previously published work is performed and the results are found to be in a good agreement. The influence of pertinent parameters such as Rayleigh number (104 ≤Ra≤107) and solid volume fraction of nanoparticles (0≤Φ≤0.15 step 0.05) on the flow, temperature, and entropy generation are examined in the present paper. The results show that the heat transfer rate increases with an increase of the Rayleigh number and the nanoparticles volume fraction. The system irreversibility increases as nanoparticles fraction increase.