Numerical Analysis of Mixed Convection in a Trapezoidal Cavity Filled with a Hybrid Nanofluid

Abstract

In this thesis, a two-dimensional numerical simulation was conducted to investigate mixed convection heat transfer in a trapezoidal cavity filled with a hybrid nanofluid. The system is characterized by a hot lower wall, a colder moving upper lid, and thermally insulated vertical sidewalls. The results were analyzed using various parameters, with particular attention given to the relationship between the average Nusselt number and the Richardson number. The finite volume method was employed to solve the governing equations of the phenomenon, and the Nusselt number was calculated. The variation of the local Nusselt number along the bottom wall was evaluated under the influence of different volume fractions (φ) and Richardson number (Ri) values. Simulations were carried out for different Ri values (0.1, 1, 2, and 5) using

-Cu/water hybrid nanofluid at various volume fractions (φ = 0%, 2%, 4%, and 8%). The results demonstrated that the addition of nanoparticles to the base fluid enhances heat transfer, particularly with increasing nanoparticle concentration a nd Richardson number. The effect of nanoparticles was found to be more significant in natural convection-dominated regimes than in forced convection. The best thermal performance was observed at φ = 8% and Ri = 5, resulting in a 39.15% enhancement, representing the optimal case in this study. These findings suggest that nanofluids can be effectively used to reduce energy consumption.