Author:
ZHOU Y.,ZHANG H. J.,YIU M. W.
Abstract
This work is an experimental study of the turbulent vortex structures, and heat
and momentum transport in the wake of two side-by-side circular cylinders. The
spacing T between the cylinder axes was varied from 1.5d to 3d (d is the cylinder
diameter). Both cylinders were slightly heated. A movable three-wire probe measured
the velocity and temperature fluctuations, and an X-wire provided a phase reference.
Measurements were conducted at x/d = 10, 20 and 40 at a Reynolds number of
5800 (based on d and the free-stream velocity U∞). At T/d = 1.5, the phase-averaged
velocity and temperature fields display a single vortex street. The two rows of vortices
exhibit a significant difference in the maximum vorticity, size and lateral distance
from the flow centreline. As T/d is increased to 3.0, the flow is totally different. Two
antiphase streets occur initially. They are less stable, with vortices weakening faster,
than the street at T/d = 1.5. By x/d = 40, one street only is identifiable. Effective
vorticity flux density indicates that, while the outer vortex nearer to the free stream
interacts largely with the adjacent oppositely signed inner vortices located near the
flow centreline, the inner vortex interacts with the cross-stream inner vortices as well
as with adjacent outer vortices. As a result, vorticity associated with the inner vortex
is annihilated quicker than that associated with the outer vortex, leading to the early
disappearance of inner vortices and formation of a single street. The contribution of
the coherent motion of various Reynolds-averaged quantities such as the momentum
and heat fluxes has also been quantified and discussed in conjunction with the vortex
structures of the flow and temperature fields.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
167 articles.
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