Treatment of the inlet boundary conditions in natural-convection flows in open-ended channels

Abstract

The present work deals with the numerical solution of elliptic flows encountered in open-ended channels. The important question of applying boundary conditions for pressure and velocity for these flows is considered and a new method for the application of boundary conditions at the channel inlet is proposed. It is shown that the flow reversal at the channel outlet, which appears when nonsymmetric flow conditions are present, is strongly dependent on the entrance boundary conditions for pressure. Results for the straight channel in situations where flow reversal is present are reported for a wide range of Rayleigh numbers. Solutions for L-shaped channels are also reported with the aim of demonstrating the application of the model to arbitrary channels. It is shown that for certain flow situations the use of an elliptic formulation is imperative in order to predict correctly the flow behavior in open-ended channels.