What is it about?

The analysis focuses on how d/D and L/D influence the Strouhal number St, wake topology and fluid forces on the downstream cylinder and link them with the flow physics.

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Why is it important?

The flow is classified into the reattachment and co-shedding flow regimes, the latter being further subdivided into the prime vortex shedding (PVS), two-layer vortex shedding (TVS) and secondary vortex shedding (SVS) modes., and Tthe detailed facet aspects of the three modes is are discussed based on the time-averaged flow fields. It is found that the The double two vortex frequencies of the downstream cylinder can be detected only in the SVS mode, and the shedding of the secondary vortex results in the additional subharmonic frequency f2 (in addition to the fundamental vortex frequency f1), the shedding of the secondary vortex further results in the flow in the subharmonic frequency f2 .

Perspectives

Only when the secondary shedding length Ls*<10" , does f2 affect the downstream cylinder will be affected by f2 and leadslead to a pattern of alternatinge high- and low-amplitude peaks in the time history of the lift coefficient. A novel mechanism of secondary vortex formation is identified., and Tthe critical spacing and the modulation of lift by f2 are also discussed.

Xiangjun Shan
Liaoning Technical University

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This page is a summary of: Effect of an upstream cylinder on the wake dynamics of two tandem cylinders with different diameters at low Reynolds numbers, Physics of Fluids, August 2021, American Institute of Physics,
DOI: 10.1063/5.0060065.
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