Numerical investigation of combined heat transfer (mixed convection-radiation) in 2D channel using the LBM

Abstract

In this paper, the problem of combined convection (forced and natural) and radiation heat transfer between two parallel plates (channel) with isothermal walls has been numerically studied. For this purpose, the equations of momentum, energy and radiation transfer must be solved. In this study, lattice Boltzmann method is used to solve all of the equations simultaneously, that, to increase the stability for solving the energy equation by lattice Boltzmann method, a modern approach called the two relaxation time model was used. The medium inside the channel was considered as a participating medium to solve the radiation transfer equation. Finally, after the formulation of governing equations and boundary conditions for the present problem in the lattice Boltzmann method, validating the results and simultaneously solving the equations, the effects of some parameters such as optical thickness, Planck number and Richardson number with changing the angle of the channel are studied on heat transfer, flow and temperature distribution. The results showed that the radiation parameters have a significant effect on the problem and can change the velocity and temperature distribution of the channel. In between these parameters, the Planck number has the most effect on the temperature and velocity of the fluid flow. Increasing the angle of the channel relative to the horizon increases the effect of buoyancy force, fluid velocity variations and fluid temperature values.