Journal article
Influence of plane boundary proximity on the Honji instability
Journal of Fluid Mechanics, Vol.852, pp.226-256
10/10/2018
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Abstract
This paper presents a numerical investigation of oscillatory flow around a circular
cylinder that is placed in proximity to a plane boundary that is parallel to the cylinder
axis. The onset and development of the Honji instability are studied over a range of
Stokes numbers (β) and gap-to-diameter ratios (e/D) at a fixed Keulegan–Carpenter
number (KC =2). Four flow regimes are identified in the (e/D, β)-plane: (I) featureless
two-dimensional flow, (II) stable Honji vortex, (III) unstable Honji vortex and (IV)
chaotic flow. As e/D increases from −0.5 (embedment) to 1, the critical Stokes
number βcr for the onset of the Honji instability follows two side-by-side convex
functions, peaking at the connection point of e/D = 0.125 and reaching troughs
at e/D = 0 and 0.375. The Honji instability is always initiated on the gap side
of the cylinder surface for 0.375 6 e/D 6 2 and occurs only on the top side for
−0.5 6 e/D < 0.125. The location for the initiation of the Honji instability switches
from the gap side to the top side of the cylinder surface for 0.125 < e/D < 0.375.
No Honji instability is observed at e/D = 0.125, where the flow three-dimensionality
is developed through a different flow mechanism. Consistently, the three-dimensional
kinetic energy of the flow, which represents a measure of the strength of flow
three-dimensionality, varies with e/D in a trend opposite to that of βcr. Three physical
mechanisms are identified as being responsible for the observed variation trend of βcr
with e/D and for various flow phenomena, which are the blockage effect induced by
the geometry setting, the existence of the Stokes layer on the plane boundary and the
favourable pressure gradient in the flow direction over the gap between the cylinder
and the plane surface.
Details
- Title
- Influence of plane boundary proximity on the Honji instability
- Creators
- Chengwang Xiong - Hebei University of TechnologyLiang Cheng - University of Western AustraliaFeifei Tong - University of Western AustraliaHongwei An - University of Western Australia
- Publication Details
- Journal of Fluid Mechanics, Vol.852, pp.226-256
- Publisher
- Cambridge University Press
- Number of pages
- 31
- Identifiers
- 991013042413202368
- Academic Unit
- Faculty of Science and Engineering
- Language
- English
- Resource Type
- Journal article