Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

UNSTEADY FORCED CONVECTION FOR A DEVELOPING FLOW IN A NON SYMMETRIC PERIODIC CHANNEL

Get access (open in a dialog) DOI: 10.1615/IHTC13.p20.20
9 pages

Abstrakt

In this study we analyse the spatio-temporal evolution of the natural instabilities in a non symmetric wavy channel - a flat plate facing a 2D wavy wall - for a laminar developing flow. The relationship between the spatial structures and intensity of these natural fluctuations on the convective heat transfer is investigated. For a Reynolds number large enough, greater than the critical Reynolds number given by the linear stability, the hydrodynamic entry fluctuations are naturally amplified along the channel until reaching a saturation level. The spatio-temporal structure of the developing flow is in good agreement with the more unstable modes obtained by the linear stability analysis. The wave length of the saturated fluctuations is not equal to the spatial geometric period but corresponds to the maximum of the temporal amplification rate. The spatial amplification rate is directly linked with the temporal one by means of the group velocity. For the thermal point of view, beyond the saturated position, we observe a local heat transfer increase due to these macroscopic fluctuations. Spatially periodic heat flux density boundary condition will allow us to find an optimum position for the wavy wall and inlet velocity characteristics to obtain local convective heat transfer optimum.