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Spanwise correlations in the wake of a circular cylinder and a trapezoid placed inside a circular pipe

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Title Spanwise correlations in the wake of a circular cylinder and a trapezoid placed inside a circular pipe
 
Creator VENUGOPAL, A
AGRAWAL, A
PRABHU, SV
 
Subject LOW REYNOLDS-NUMBERS
VORTEX FLOWMETER
BLUFF-BODY
ASPECT RATIO
FREQUENCY
PLATE
FLOW
3-DIMENSIONALITY
PERFORMANCE
VORTICES
Spanwise correlation
Circular cylinder
Trapezoid
Confined pipe
Correlation length
 
Description The spanwise correlation of a circular cylinder and a trapezoidal bluff body placed inside a circular pipe in fully developed turbulent regime is studied using hotwire anemometer. The present configuration possesses complex fluid structure interaction owing to the following features: high blockage effect; low aspect ratio of the body; upstream turbulence and interaction of axisymmetric flow with a two dimensional bluff body. The spatial correlation of such configuration is seldom reported in the literature. Results are presented for Reynolds number of Re-D=1 x 10(5). Three different blockage ratios (0.14, 0.19 and 0.28) are considered in the present study. Correlation coefficient is observed to improve with increase in blockage ratio. Compared to a circular cylinder, a trapezoidal bluff body possesses high correlation length. The near wall effects tend to increase the phase drift, which is reflected in low correlation coefficients close to the pipe wall. The results show that the simultaneous effect of curvature, low aspect ratio and upstream turbulence reduces the correlation coefficients significantly as compared to unconfined and confined (parallel channel) flows. The low frequency modulations with a circular cylinder are higher for lower blockage ratios. The three-dimensionality of vortex shedding for trapezoid with a blockage ratio of 0.28 was observed to be lower compared to circular cylinder and all other blockage ratios. Low frequency modulations were found to be responsible for weak vortex shedding from a circular cylinder compared to a trapezoidal bluff body. The vortex shedding is observed to be nearly two dimensional in case of a trapezoidal bluff body of blockage ratio 0.28. (C) 2014 Elsevier Ltd. All rights reserved.
 
Publisher ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
 
Date 2016-01-14T14:22:32Z
2016-01-14T14:22:32Z
2015
 
Type Article
 
Identifier JOURNAL OF FLUIDS AND STRUCTURES, 54,536-547
0889-9746
http://dx.doi.org/10.1016/j.jfluidstructs.2014.12.008
http://dspace.library.iitb.ac.in/jspui/handle/100/17716
 
Language en