Library Subscription: Guest
Begell Digital Portal Begell Digital Library eBooks Journals References & Proceedings Research Collections
Computational Thermal Sciences: An International Journal

ISSN Print: 1940-2503
ISSN Online: 1940-2554

Computational Thermal Sciences: An International Journal

DOI: 10.1615/ComputThermalScien.2016015572
pages 31-47

SIMULATION OF NATURAL CONVECTION OF NANOFLUIDS AT HIGH RAYLEIGH NUMBERS: A TWO-COMPONENT LATTICE BOLTZMANN STUDY

Mehdi Hosseini Abadshapoori
Center of Excellence in Energy Conversion (CEEC), Mechanical Engineering Department, Sharif University of Technology, P.O. Box: 11155-9567, Tehran, Iran
Mohammad Hassan Saidi
Center of Excellence in Energy Conversion, School of Mechanical Engineering, Sharif University of Technology, P.O. Box: 11155-9567, Azadi Avenue, Tehran, Iran

ABSTRACT

In this research, the effect of using nanoparticles on the Nusselt number in the natural convection at high Rayleigh numbers has been investigated. A two-component multiple relaxation times lattice Boltzmann code has been developed to investigate the natural convection of nanofluids in a 2D square enclosure. Three main forces, namely, buoyancy, drag, and Brownian forces are included to consider the interactions of the components. The potential force is also added to the model for the interactions among nanoparticles. The effects of Ra number, volume fraction of nanoparticles (φ), and size of nanoparticles (λ) have been investigated for two nanofluids (CuO-water and TiO2-water). Five different volume fractions (0.01−0.05) have been simulated while the Rayleigh number has been selected among 106, 107, 108, and 109. Four different sizes, namely, 10, 30, 60, and 80 nm have been used for the nanoparticles. Results reveal that Nusselt number increases with the increase of φ. However, it is shown that adding nanoparticles also increases viscosity which reduces the positive effect of nanoparticles on the Nu number. Results also show that an increase in the λ results in the decrease in the Nusselt number. The method is shown to have good capability of simulating nanofluids in natural convection at high Rayleigh numbers considering the effect of nanoparticles.