Laminar and Turbulent Convection in Cavities: Numerical Modeling and ExperimentalValidation

摘要

A numerical and experimental study of natural convection in rectangularenclosures in a large range of Rayleigh numbers up to 10(exp 12) is presented. The equations and boundary conditions that govern the turbulent three dimensional natural convective flow are presented. Some approximations and their restrictions are discussed. Closely related to these approximations are the characteristic velocity and length scales for the different Rayleigh numbers. Temperature and heat transfer measurements by holographic interferometry and velocity and velocity fluctuation measurements by means of laser Doppler anemometry are described. The numerical method used to solve the governing equations is described with special attention given to convergence and stability. The results of the numerical simulations are reported: results for air and water as the working fluid are classified into four Rayleigh number ranges; for various Rayleigh numbers, results of grid refinement tests are discussed indicating the accuracy of the numerical method; the influence of the upper and lower horizontal walls on the vertical wall heat transfer is presented; computations in three dimensional enclosures provide information on the importance of lateral sidewall effects; results for inclined cavities are presented. The model was used to calculate two dimensional natural convection in a room.