Mixed convection heat transfer of nanofluids in a lid driven square cavity: A parametric study

Laminar mixed convection heat transfer in a lid driven square cavity filled with nanofluids is investigated numerically. In this current study, the vertical walls are purported at steady but dissimilar temperatures, whereas the bottom and top horizontal walls are insulated. The top wall is set with uniform velocity and insulated. Al₂O₃, CuO, SiO₂ and TiO₂ are the nanoparticles used with diameters 25nm, 40nm and 60nm. Results are presented in terms of streamlines, isotherms and Nusselt number for different parameters such as, the Reynolds number (700≤Re≤1600), the Rayleigh number(10⁴≤ Ra≤ 10⁶) and the volume fraction 0≤φ≤ 0.04. It was found that Al₂O₃-H₂O has the highest Nusselt number, followed by TiO₂-H₂O, SiO₂-H₂O and lastly CuO-H²O. Nusselt number is higher for nanofluids compared to pure water. It was noted that with the increment in volume fraction, Nusselt number increases but with larger diameter of nanoparticles it reduces. Increase in the Reynolds number resulted in higher Nusselt number. Higher difference between the hot and cold walls also results in higher Nusselt numbers.