Attenuation of radiative heat transfer in natural convection from a heated plate by scattering properties of Al2O3 nanofluid: LBM simulation

• Published in: International journal of mechanical sciences Vol. 156; pp. 250 - 260
• Main Authors: Sobhani, Masoud, Tighchi, Hashem Ahmadi, Esfahani, Javad Abolfazli
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2019
• Subjects: Heated plate; Lattice Boltzmann method; Nanofluid; Natural convection; Radiative properties; Volumetric radiation; Heated plate; Volumetric radiation; Natural convection; Lattice Boltzmann method; Radiative properties; Nanofluid
• ISSN: 0020-7403; 1879-2162
• DOI: 10.1016/j.ijmecsci.2019.04.003

•Effect of radiative heat transfer on natural convection from a heated plate in the cavity with Al2O3 nanofluid is studied.•The LBM is used to solve the flow, energy and radiative equations of the nanofluid in the cavities with the heated plate.•In the presence of radiation, the total Nusselt number decreases when the volume fraction of nanoparticles increases.•For vertical heated plate case the total Nusselt number at Ra = 105 and ϕ = 0.1% is 26% more than the radiation absence.•For horizontal heated plate case the total Nusselt number at Ra = 105 and ϕ = 0.1% is 23% more than the radiation absence. In this paper, the lattice Boltzmann method (LBM) is extended to simulate combined volumetric radiation and natural convection in a nanofluid filled the cavity with an inside heated plate. Accordingly, all of the governing equations, including the radiative equation, are solved by the LBM approach. Also, the Rayleigh theory is adopted to find the optical properties of nanofluid. The nanofluid is a mixture of Al2O3 nanoparticles suspended in pure water as a base fluid. Main efforts focus on the effects of volumetric radiation at different Rayleigh numbers (103, 104 and 105) and volumetric concentrations (0.1% and 0.3%) on the flow and temperature distribution inside the enclosure for the horizontal and vertical heated plate. The obtained results indicate that considering thermal radiation noticeably affects temperature patterns. It is also observed that the average Nusselt number is improved by reason of radiation presence, whereas it decreases with increasing volume concentration due to the increase of scattering properties of the nanofluid. The present results reveal that the used LBM for solving the radiation transport equation, instead of approximations, provides new findings that should be considered in practical applications. [Display omitted]