Transient air natural convection in asymmetrically heated vertical channels

摘要

A numerical analysis of natural convection in air in a vertical channel asymmetrically heated at uniform heat flux is carried out in this work. One channel wall is heated whereas the other one is adiabatic, and the problem is transient, two-dimensional and laminar. Constant and variable property models are considered. For both models, numerical solution is obtained by means the commercial CFD code Fluent. An extended computational domain is considered in order to simulate the far field conditions and it consists of the channel geometry with an upstream reservoir and a downstream reservoir. Simulations are achieved for Rayleigh number, Ra, values in the range 10~2-10~6 and results are showed as temperature profiles along the heated wall as a function of time, stream function and temperature fields. The present analysis allows to improve the knowledge of the effects related to the variable properties on the inlet and outlet zone and consequently inside the channel by numerical investigation during the development of fluid dynamic and thermal fields which are strongly linked. The results give quantitative information on the errors due to the use of constant properties model with respect to the variable properties model in natural convection in asymmetrical heated vertical channels.