Abstract
Three-dimensional (3-D) transition in the wake of two tandem co-rotating cylinders is studied numerically for Reynolds numbers
$180\le Re\le 500$
. Infinite cylinders of equal diameter (
$D$
) and span (
$8D$
) are placed at streamwise gaps
$Lx=2.5D$
and
$7.5D$
, and rotated at rotation rates
$\alpha =0$
,
$0.5$
,
$1$
and
$2$
. For
$\alpha =0$
and
$Lx=7.5D$
, 3-D transition in the wake of the upstream cylinder resembles that for an isolated cylinder with the formation of Mode-A and Mode-B instabilities, whereas for the downstream cylinder, only Mode-A instability occurs in both the
$Lx=2.5D$
and
$7.5D$
cases with
$\alpha =0$
. When the cylinders rotate at
$\alpha =1$
for
$Lx=7.5D$
, staggered transition takes place with the appearance of only Mode-B and only Mode-A instabilities in the near-wake regions of the upstream and downstream bodies, respectively. In the case
$Lx=2.5D$
, the wake of the rotating cylinders transitions via Mode-C and Mode-D instabilities for
$\alpha =0.5$
, Mode-D and Mode-D
$^\prime$
for
$\alpha =1$
, and Mode-C and Mode-A for
$\alpha =2$
. A sudden decrease in near-wake fluctuations, accompanied by a downward jump in the force coefficients, is observed as the 3-D instability shifts from one mode to another, for
$\alpha \ge 1$
and
$Lx=2.5D$
. This discontinuity is caused by the formation of a pair of opposite-signed recirculation zones that mitigate each other's effects in the near-wake region.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,Applied Mathematics
Cited by
4 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献