DNS in evolution of vorticity and sign relationship in wake transition of a circular cylinder: (pure) mode A

Lin, Liming; Zhirong, Tan

doi:10.1007/s10409-019-00889-4

Cited by 11 publications

(7 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the perspective of vorticity as the main variable to describe the intensity of a vortex, it suggests that streamwise vorticity in these streamwise vortices is also generated by this coupling mechanism. However, as indicated in previous work (Lin and Tan 2019b), pure mode A could occur at a lower Reynolds number, although spanwise vortices seem to be undisturbed. Such phenomena manifest an obvious paradox in the previous coupling mechanism that the streamwise vorticity is already generated but the primary vortex core is still stable with 2D features at a lower Reynolds number.…”

Section: Introductionsupporting

confidence: 67%

“…The total element number of the present 2D standard mesh, N xy , is 20 100. As already analyzed and reported in previous works (Henderson 1997, Lin andTan 2019b), a uniform spanwise grid size, ∆z = 0.1, is adopted.…”

Section: Computational Domain and Meshmentioning

confidence: 99%

“…However, when the Reynolds number is greater than 195, obvious 3D wake flow and a sudden drop in fluid forces with L Z = 4 are referred to as the fully developed pure mode A, as the second stage. The detailed investigation into the fully developed stage of pure mode A can be referenced in a previous work (Lin and Tan 2019b). Here, the main focus is put on the initially generated stage in a range of Reynolds numbers from 150 to 195 with L Z = 4.…”

Section: Features Of Fluid Forcesmentioning

confidence: 99%

“…Experimental measurements were carried out by Meiburg and Lasheras (1988), Kamemoto (1992, 1993), Williamson (1996aWilliamson ( , 1996b, Prasad and Williamson (1997), Leweke and Williamson (1998), Luo et al (2003), for example. Thanks to advances in computation technology, direct numerical simulations (DNSs), adopting the finite volume method or spectral element method, have become increasingly common tools in recent decades (Meiburg and Lasheras 1988, Karniadakis and Triantafyllou 1992, Wu and Ling 1993, Persillon and Braza 1998, Darekar and Sherwin 2001, Posdziech and Grundmann 2001, Jiang et al 2016, 2017, Agbaglah and Mavriplis 2017, Lin et al 2018, 2019a, Jiang and Cheng 2019, Lin and Tan 2019b, 2022. Some theoretical methods, including linear and nonlinear stability analysis, typically for Floquet stability analysis, are sometimes adopted under certain circumstances (Barkley and Henderson 1996, Henderson 1997, Ling and Chang 1999, Barkley et al 2000, Posdziech and Grundmann 2001, Thompson et al 2001, Sheard et al 2003, Rao et al 2013, Clainche et al 2018, Lin et al 2019c.…”

Section: Introductionmentioning

confidence: 99%

“…Because of no sufficient research involving the possible emergence of pure mode A in the near wake at lower Reynolds numbers less than 195 (Williamson 1996a, Jiang et al 2016, Lin and Tan 2019b or before St suddenly jumps and primary vortex cores become unstable, the primary aim of the present study is to investigate such transitional phenomenon through DNS. If such a transitional stage exists, the spatiotemporal evolution of vorticity and its sign relationships in the near wake and on cylinder surfaces and other features can be further analyzed and compared with those in pure mode A at Re ⩾ 195.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Initially generated pure mode A in the three-dimensional wake transition of a circular cylinder

Lin¹

2022

Fluid Dyn. Res.

View full text Add to dashboard Cite

The initially generated pure mode A, as a transitional stage, is investigated in the three-dimensional wake transition of a circular cylinder. Direct numerical simulations are carried out over a range of Reynolds numbers from 100 to 210. According to the different dynamic behaviors of hydrodynamic parameters and similar features in the spatiotemporal evolution of vorticity in the near wake, two stages are identified. The first, investigated here, is the initial generation of pure mode A at Reynolds numbers less than 195, while the second, already reported, is the full development of pure mode A at Reynolds numbers greater than 195. The relationship between the volume-RMS (root-mean-square) vorticity and Reynolds number indicates two critical Reynolds numbers, 145 and 195 (at most). The first critical Reynolds number denotes the initial appearance of three-dimensional instability. The second critical Reynolds number indicates the transition of pure mode A from the initially generated state to the fully developed state in the near wake. After the first critical Reynolds number, the evolution of the vorticity in the near wake and on the rear surface of the cylinder clearly shows that the appearance of pure mode A is a gradual process, rather than a sudden process accompanied by a jump in vortex shedding frequency. In particular, as the Reynolds number increases, the streamwise vorticity first appears on and near the cylinder surface, then in the shear layers, and finally in the shedding primary vortices, instead of appearing instantaneously in the shedding vortices after the instability of primary vortex cores.

show abstract

Section: Introductionsupporting

confidence: 67%

Section: Computational Domain and Meshmentioning

confidence: 99%

Section: Features Of Fluid Forcesmentioning

confidence: 99%