Lattice Boltzmann simulation of free convection in nanofluid filled cavity with partially active walls – entropy generation and heatline visualization

• Published in: International journal of numerical methods for heat & fluid flow 2018-10, Vol.28 (10), p.2254-2283
• Main Authors: Rahimi, Alireza, Kasaeipoor, Abbas, Hasani Malekshah, Emad, Kolsi, Lioua
• Format: Article
• Language: English
• Subjects: Boundary conditions; Carbon nanotubes; Computational fluid dynamics; Computer simulation; Convection; Dynamic viscosity; Entropy; Flow structures; Fluid flow; Fluids; Free convection; Heat conductivity; Heat transfer; Holes; Investigations; Methods; Nanofluids; Nanotechnology; Numerical analysis; Nusselt number; Parameters; Physical properties; Rayleigh number; Researchers; Simulation; Temperature; Thermal conductivity; Two dimensional analysis; Velocity; Viscosity; Visualization; Walls
• ISSN: 0961-5539; 1758-6585
• DOI: 10.1108/HFF-06-2017-0229

Purpose This paper aims to perform the lattice Boltzmann simulation of natural convection heat transfer in cavities included with active hot and cold walls at the side walls and internal hot and cold obstacles. Design/methodology/approach The cavity is filled with double wall carbon nanotubes (DWCNTs)-water nanofluid. Different approaches such as local and total entropy generation, local and average Nusselt number and heatline visualization are used to analyze the natural convection heat transfer. The cavity is filled with DWCNTs-water nanofluid and the thermal conductivity and dynamic viscosity are measured experimentally at different solid volume fractions of 0.01 per cent, 0.02 per cent, 0.05 per cent, 0.1 per cent, 0.2 per cent and 0.5 per cent and at a temperature range of 300 to 340 (K). Findings Two sets of correlations for these parameters based on temperature and solid volume fraction are developed and used in the numerical simulations. The influences of different governing parameters such as Rayleigh number, solid volume fraction and different arrangements of active walls on the fluid flow, heat transfer and entropy generation are presented, comprehensively. It is found that the different arrangements of active walls have pronounced influence on the flow structure and heat transfer performance. Furthermore, the Nusselt number has direct relationship with Rayleigh number and solid volume fraction. On the other hand, the total entropy generation has direct and reverse relationship with Rayleigh number and solid volume fraction, respectively. Originality/value The originality of this work is to analyze the two-dimensional natural convection using lattice Boltzmann method and different approaches such as entropy generation and heatline visualization.