Stability of flows past a pair of circular cylinders in a side-by-side arrangement

Mizushima, Jiro; Ino, Y.

doi:10.1017/s0022112007009433

Cited by 54 publications

(34 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many researchers suggested that the flow behind two side-by-side cylinders is mainly governed by the two non-dimensional parameters of Reynolds number (Re) and gap ratio, g* (g/D), where g is the spacing between 2 cylinders (Williamson, 1985;Kang, 2003;Mizushima and Ino, 2008;Carini et al, 2014). For square cylinders, the length of one edge is usually used as characteristic length D for both Re and g*.…”

Section: Introductionmentioning

confidence: 99%

Wake of two side-by-side square cylinders at low Reynolds numbers

Kang

Lim

et al. 2017

Physics of Fluids

View full text Add to dashboard Cite

Wake of two side-by-side square cylinders was investigated through direct numerical simulation at low Reynolds numbers (16~200). The gap between the two cylinders varied from 0-10D, where D is the dimension of the square cylinder (edge length). 9 different wake patterns and their dependency on both Reynolds number and gap spacing were identified and analysed. A system classification map, demarcated by Reynolds number and gap ratio g* (g/D, where g is the gap spacing between 2 cylinders), was derived for these 9 wake modes. Steady-state wake (mode I) was observed when Reynolds number is lower than the critical Reynolds number, which depends on g*. For gap ratio less than 0.7, only single vortex street was observed. The single vortex street wake can be either symmetric and periodic (mode II), or asymmetric and periodic (mode III), or irregular (mode IV). In this gap ratio range (less than 0.7), shedding frequency decreases with gap ratio due to the damping role of the gap flow. For gap ratio larger than 0.7, two vortex streets were also observed. For gap ratio larger than 1, only two vortex streets were observed. Vortex shedding can be either synchronized and in-phase (mode V), synchronized and anti-phase (mode VI), in-phase dominated with low frequency modulation (mode VII), anti-phase dominated with low frequency modulation (mode VIII), asymmetric synchronized anti-phase (mode IX), or irregular (mode IV). For gap ratio larger than 4, only synchronized anti-phase mode was observed under the conditions of this study. In the two vortex streets regime, shedding frequency is higher than that of a single cylinder, due to stronger gap flow than that in the freestream side. The impact of gap ratio and Reynolds number on the drag and lift forces was also studied.2

show abstract

Section: Introductionmentioning

confidence: 99%

Wake of two side-by-side square cylinders at low Reynolds numbers

Kang

Lim

et al. 2017

Physics of Fluids

View full text Add to dashboard Cite

show abstract

“…the symmetric base flow obtained by the Newton-Raphson method. For the employed parameters, in [12] was shown that two different global modes become linearly unstable: a steady, antisymmetric mode and an in-phase vortex shedding oscillatory mode. In our simulations, for Re = 68.8 and g = 0.7, the flow first evolves towards an oscillation analogous to the in-phase limit cycle.…”

Section: Dns Resultsmentioning

confidence: 99%

“…This hypothesis was supported by Mizushima and Ino [12], who computed the linear stability of the symmetric, steady base flow, because they found a narrow region in the parameter space where this flow bifurcates to an asymmetric steady solution.…”

mentioning

confidence: 75%

See 1 more Smart Citation

Secondary Instability of the Flow Past Two Side-by-side Cylinders

Carini

Auteri

Giannetti

2016

Notes on Numerical Fluid Mechanics and Multidisciplinary Design

View full text Add to dashboard Cite

In this work the flip-flop instability occurring in the flow past two sideby-side circular cylinders is numerically investigated at a fixed nondimensional gap spacing of g = 0.7 and within the range of Reynolds numbers 60 < Re ≤ 90. The inherent two-dimensional flow pattern is characterized by an asymmetric unsteady wake (with respect to the horizontal axis of symmetry) and the gap flow is deflected alternatively toward one of the cylinders. Such behaviour has been ascribed by other authors to a bi-stability of the flow, and therefore termed flip-flop. On the contrary, the simulations performed herein provide new evidence that at low Reynolds numbers the flip-flopping state develops through an instability of the in-phase synchronized vortex shedding between the two cylinder wakes. This new scenario is confirmed and explained by means of a global linear stability investigation of the in-phase periodic base flow. The Floquet analysis reveals indeed that a pair of complex-conjugate multipliers becomes unstable above the critical threshold of Re = 61.74 having the same low frequency as the gap flow flip-over.

show abstract

“…Of particular interest is to ascertain when the flow first becomes unstable and the mode of instability. Experiments, see for example Mizushima & Ino (2008), for the flow past two such cylinders show a complicated dynamics as the parameters are varied. For large Reynolds numbers, and for large gap widths the flow is like that past an isolated cylinder and the observed shedding frequencies also similar.…”

Section: Flow Past Circular Cylindersmentioning

confidence: 99%