Natural convection heat transfer in a nanofluid filled L-shaped enclosure with time-periodic temperature boundary and magnetic field

The natural convective Cu-water nanofluid flow in L-shape cavity with an oscillating temperature profile is studied numerically. The cavity's lower horizontal and left vertical walls are heated sinusoidally with time about a high mean temperature (T¯_H). In contrast, the cavity's right vertical wall and its nearby horizontal lower wall are kept cold at a temperature (T_c). The calculations have been performed over temperature oscillation amplitude (0≤A≤2), dimensionless temperature oscillation frequency 0≤f≤100, Rayleigh number (10³≤Ra≤10⁸), Hartmann number (0≤Ha≤100), the nanoparticles volume fraction (0≤ϕ≤0.2), and enclosure aspect ratios (0.2≤AR≤0.8). Outcomes reveal that with AR = 0.2, heat transfer happens considerably through conduction at Ra = 10³ –10⁵, while the time average Nusselt number (Nu¯) is independent of both Ha and Ra. Convection effects, on the other hand, become significant at high Ra. Additionally, as Ha ascends from 0 to 50, Nu¯ increases linearly with increasing ϕ, while it remains steady at Ha = 75 and 100.