Impact of hybrid wavy wall heating on magnetohydrodynamic Cu–water nanofluid convection heat transfer with irreversibility assessment

Abstract

Heat and irreversibility characteristics of magnetohydrodynamic convection within copper–water nanofluid-filled enclosure featuring innovative hybrid undulated boundary configurations are examined. The analysis focuses on understanding variations in hybrid undulated wall geometry, combined with magnetic influences, affecting hydrothermal behavior inside a porous cavity. Finite element techniques solve conservation principles considering nanoparticle concentration (φ), Hartmann number (Ha), and Rayleigh number (Ra) as control parameters. Additionally, undulation frequencies (n) and amplitudes (λ) of the hot hybrid boundary are also considered. Results demonstrate that larger undulation amplitudes and increased frequency generally improve thermal transport, with optimal configuration occurring at four undulations (n = 4). However, further increases in yield diminish returns, indicating optimal design limits for maximizing thermal transport. Externally applied magnetic fields noticeably weaken circulating fluid motion, consequently reducing convective transport effectiveness. Initially, increasing nanoparticle concentration enhances thermal conductivity, but higher concentrations increase fluid viscosity, impeding flow and reducing transport efficiency. While adding boundary undulations improves thermal transport, it simultaneously raises irreversibility production, highlighting a balance between enhancing thermal exchange and minimizing energy loss. Ra increases from 103 to 106 could enhance Nu by approximately 29% (relative to the straight boundary), depending on λ. Increases in λ from 0 to 0.3 lead to increased effective heated surface and thus higher heat transport. At λ = 0.2 and n = 2, average Nu enhances up to 29.14%. Corresponding irreversibility production also increases proportionally. Overall, NS might experience a 40–45% increase across the Ha range, depending on λ. These analyses offer practical insights for designing advanced thermal systems, particularly thermal exchangers, where optimizing both thermal transport efficiency and energy conservation remains essential.