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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Comparative Study of Numerical Simulations of a 2D Buoyancy-Driven Flow in a Vertical Channel Asymmetrically Heated with or without the External Domain

Get access (open in a dialog) DOI: 10.1615/IHTC15.ncv.009291
pages 5371-5385

Resumo

This work aims at improving the numerical modelling of 2D buoyancy-driven flows in a vertical channel asymmetrically heated, whose main difficulty lies in the definition of boundary conditions at the top and bottom ends of the channel. Two approaches have been investigated for identifying the influence of the external surroundings of the channel on the flow developing in the channel. In the first approach the computational domain includes the channel and its external environment, while in the second, it is restricted to the geometrical limits of the channel. The 2D unsteady Boussinesq equations are solved for two Rayleigh numbers corresponding either to a fully developped regime or to a boundary layer regime. Firstly, the influence of the tank size on the channel flow is characterized. For both regimes, instantaneous fields are selected at times for which the channel flow can be considered of the tank size. From these reference solutions, the pressure distributions on the interfaces have been extracted. Three sets of boundary conditions at the interfaces are tested: standard local Bernoulli boundary conditions and two sets using the extracted pressure profiles with either homogeneous Neumann or zero tangential stress conditions for velocities. By comparing both approaches, it is shown that a good agreement in terms of global quantities is obtained whatever the boundary conditions. However the flow at the interfaces is not well predicted except if a part of the external environment (i.e. the pressure) is introduced and a zero tangential stress is considered at the bottom entrance.