Natural and Mixed Convection Study of Isothermally Heated Cylinder in a Lid-Driven Square Enclosure Filled with Nanofluid

A computational study of an isothermally heated circular cylinder which has been locomoted at different locations within a square enclosure is investigated numerically using finite volume method. The numerical work is conducted to acquire the heat transfer details through steady, laminar, natural and mixed convection in the enclosure filled with pure water and Al2O3–water nanofluid. The study is performed for different restraints such as cylinder position (CP1–CP9), nanoparticles volume fractions (0 ≤ ϕ ≤ 0.05), Richardson number (Ri = 0.1–10) and Rayleigh number (105–107). The results are exhibited qualitatively in terms of streamlines and isotherms however quantitatively by local and average Nusselt number for various constraints. The results unfolded from investigation that the average Nusselt number is significantly changed with the cylinder locations and is found maximal at the cylinder position CP2. The investigation is further explored at this position of cylinder. It is found that the average Nusselt number enhances in addition, with the increment of nanoparticle concentrations, for lower value of Richardson number and higher values of Rayleigh number.