Comprehensive analysis of MHD hybrid nanofluid mixed convection and entropy generation in an open enclosure

This study numerically investigates the combined effects of buoyancy force, magnetic field, and hybrid nanoparticle concentration on the hydrodynamic and thermal behavior, as well as flow irreversibility, in an open enclosure. The working fluid is a hybrid nanofluid composed of water, copper, and copper oxide nanoparticles. The governing equations for two-dimensional, laminar, incompressible flow are solved using the finite volume method coupled with the SIMPLE algorithm, while entropy generation rate, based on the second law of thermodynamics, quantifies flow irreversibility. The influences of the Grashof number 0 ≤ Gr ≤ 2 × 10 5 , Hartmann number 0 ≤ Ha ≤ 20 and hybrid nanoparticles concentration 0 ≤ ϕ ≤ 0.06 on streamlines, friction coefficients, isotherms, Nusselt numbers and entropy generation numbers are systematically analyzed. The results indicate that increasing buoyancy force enhances wall friction, heat transfer rate, and entropy generation, whereas a stronger magnetic field suppresses these parameters. Moreover, the addition of hybrid nanoparticles intensifies wall friction and flow irreversibility, whereas it slightly reduces the average Nusselt number under buoyancy-dominated conditions. Specifically, the maximum values of average friction coefficient and total entropy generation number occur at Gr = 2 × 10 5 , ϕ = 0.06 , Ha = 0 , with increases of 18.15 % and 34.14 % , respectively, relative to the reference case Gr = 0 , ϕ = 0 , Ha = 0 , whereas the maximum average Nusselt number occurs at Gr = 2 × 10 5 , ϕ = 0 , Ha = 0 , with an increase of 47.36 % relative to the corresponding reference case. The present study employs a rigorous numerical methodology, including discretization, solution algorithms, grid-independence study, convergence criteria, and code validation, to ensure accurate and reliable results. These findings provide valuable insights and practical guidelines for the design and optimization of advanced thermal systems employing magnetic hybrid nanofluids.