TITLE:
Role of Surface Roughness during Natural Convection
AUTHORS:
M. Yousaf, S. Usman
KEYWORDS:
Natural Convection, Rayleigh Number, Surface Roughness, Heat Transfer, Lattice Boltzmann Method
JOURNAL NAME:
World Journal of Engineering and Technology,
Vol.3 No.3C,
October
22,
2015
ABSTRACT:
A computational study was performed in a
two-dimensional square cavity in the presence of roughness using an algorithm
based on mesoscopic method known as Lattice Boltzmann Method (LBM). A single
relaxation time Bhatnagar-Gross-Krook (BGK) model of LBM was used to perform
numerical study. Sinusoidal roughness elements of dimensionless amplitude of
0.1 were located on both the hot and cold walls of a square cavity. A Newtonian
fluid of the Prandtl number (Pr) 1.0 was considered. The range of the Rayleigh
(Ra) number explored was from 103 to 106 in a laminar region. Thermal and
hydrodynamic behaviors of fluid were studied using sinusoidal roughness
elements. Validation of computational algorithm was performed against previous
benchmark studies, and a good agreement was found. Average Nu (Nusselt number)
has been calculated to observe the effects of the surface roughness on the heat
transfer. Results showed that sinusoidal roughness elements considerably affect
the thermal and hydrodynamic behaviors of fluid in a square cavity. The maximum
reduction in the average heat transfer in the presence of roughness was
calculated to be 23.33%.