Experiments On Transient Dynamic Features
In Complex Separated Convection
Boundary Layer Flows
Author(s)
S. Fohanno, F. Beaumont & G. Polidori
Abstract
Although the fluid dynamics around an isolated heated circular cylinder are now
reasonably well understood, this is not the case when the cylinder is positioned
close to a free convection plane wall boundary layer. One mechanism by which
transitional boundary layer flows become turbulent is the instability of vortex
interaction. The core of this contribution is to present flow visualizations
showing the formation and development of resulting vortical complex structures
in the interaction of opposite naturally-induced flows. To the authors’
knowledge, these complex phenomena have not been clearly investigated and
documented. Therefore, the purpose of this study is to provide a detailed
description of the resulting transient physical mechanisms. The effect of
changing the gap between the cylinder and the wall has clearly shown the growth
in time of both dipolar vortex and shear layer instabilities and complex vortical
separations of the wall boundary layer.
Keywords: free convection, flow visualization, vortical instabilities.
1 Introduction
This purely experimental work is part of a set of studies on possible heat transfer
improvements (French research network AMETH) and is primarily concerned
with transient free convection flows in the laminar regime. In particular, this
work is dealing with the analysis of fundamental mechanisms of transient free
convection along a uniformly heated vertical plate. In addition, the growth of
both thermal and dynamical boundary layers is perturbed due to the presence of a
cooled obstacle in the vicinity of the plate. The interest for such studies comes
from their realistic nature depicting practical examples found in various domains
Keywords
free convection, flow visualization, vortical instabilities.
Related Book
Other papers in this volume
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