The vortex-shedding process behind two-dimensional bluff bodies

Perry, A. E.; Chong, M. S.; Lim, T. T.

doi:10.1017/s0022112082000378

Cited by 255 publications

(121 citation statements)

References 3 publications

Supporting

Mentioning

106

Contrasting

Order By: Relevance

“…The vortex formation is characterized by the shear layer from the other side of the wake cutting off the vorticity supply to the growing vortex from the cylinder wall, just as stated by Gerrard. 21 From a flow topology, the birth of a new vortex is associated with the formation of a saddle point, as earlier found by Perry et al 23 For Riϭ1.0, it is observed that pairs of counterrotating vortices appear directly behind the cylinder. The distance between the counterrotating vortices is exactly the same as the distance between the plumes, being twice the cylinder diameter.…”

Section: Discussionsupporting

confidence: 60%

“…5͑b͒ to 5͑c͒, the N2͑AL͒ cuts off the vorticity supply of the vortex B from the cylinder wall. The hypothesis of Perry et al 23 has been reconfirmed that the birth of a new vortex is characterized by the formation of a new saddle point in the streamline topology.…”

Section: Unheated Case: Vortex Formationmentioning

confidence: 94%

“…The hypothesis of Gerrard 21 says that a forming vortex draws the shear layer ͑of opposite sign͒ from the other side of the wake across the wake centerline, eventually cutting off the supply of vorticity to the growing vortex. To some extent this process can be understood from the instantaneous streamline patterns drawn by Perry et al 23 To relate the vortex shedding process as described by Gerrard's hypothesis and the drawn patterns of Perry et al, 23 the wake flow is visualized using particle paths for Reϭ85 and Riϭ0. The flow pattern is considered as 2D.…”

Section: Unheated Case: Vortex Formationmentioning

confidence: 99%

“…5 alleyways are shown as solid lines. It was described by Perry et al 23 that, during the starting process, the so-called ''closed'' cavity becomes open and instantaneous alleyways of fluid are formed. In Fig.…”

Section: Unheated Case: Vortex Formationmentioning

confidence: 99%

See 3 more Smart Citations

Experimental and numerical investigation of the vortex formation process behind a heated cylinder

2004

View full text Add to dashboard Cite

This paper describes the three-dimensional (3D) vortex formation process behind a heated cylinder at low Reynolds numbers. Both experimental and numerical techniques are used, including an electrochemical tin-precipitation visualization method, a two-dimensional (2D) high resolution particle velocimetry technique, and a 3D spectral element method. The wake flow is simultaneously investigated in two perpendicular planes using a “dual-plane” configuration. It appears that for Reynolds number around 100 and Richardson number larger than 1.0 thermal plumes occur in the far wake. Correspondingly distinct counterrotating vortices, with a spanwise wavelength of two cylinder diameters, are shown in the near wake. Furthermore, a difference in the flow motion for “in-plume” and “out-of-plume” positions is observed. The vortex shedding process for the “out-of-plume” positions is quite similar to the one for an unheated cylinder, which is a 2D flow. At in-plume positions, it is observed that the flow moves upward from the lower to the upper half of the wake. From the calculated temperature field, a region of unstable thermal stratification in gravity direction is observed at the in-plume positions. This indicates that the upward motion at the in-plume positions is induced by buoyancy when the temperature gradient is large enough.

show abstract

Section: Discussionsupporting

confidence: 60%

Section: Unheated Case: Vortex Formationmentioning

confidence: 94%

Section: Unheated Case: Vortex Formationmentioning

confidence: 99%

Section: Unheated Case: Vortex Formationmentioning

confidence: 99%

See 2 more Smart Citations

Experimental and numerical investigation of the vortex formation process behind a heated cylinder

2004

View full text Add to dashboard Cite

show abstract

“…For unsteady flows time can also be considered a parameter in the system (1). A general bifurcation theory for streamline patterns has been developed by several authors [28,29,30,31,32,33] and many applications to specific flow problems such as vortex breakdown [34,35], driven cavities [36,37,38], the cylinder wake [39,40] and peristaltic flows [41] are available. The analysis of topological bifurcations consists in identifying degenerate streamline patterns and their unfoldings, that is, parametrized families of velocity fields which can represent all possible perturbations of the given degenerate pattern.…”

Section: Introductionmentioning

confidence: 99%

Codimension three bifurcation of streamline patterns close to a no-slip wall: A topological description of boundary layer eruption

et al. 2015

View full text Add to dashboard Cite

A vortex close to a no-slip wall gives rise to the creation of new vorticity at the wall. This vorticity may organize itself into vortices that erupt from the separated boundary layer. We study how the eruption process in terms of the streamline topology is initiated and varies in dependence of the Reynolds number Re. We show that vortex structures are created in the boundary layer for Re around 600, but that these disappear again without eruption unless Re > 1000. The eruption process is topologically unaltered for Re up to 5000. Using bifurcation theory, we obtain a topological phase space for the eruption process, which can account for all observed changes in the Reynolds number range we consider. The bifurcation diagram complements previously analyzes such that the classification of topological bifurcations of flows close to no-slip walls with up to three parameters is now complete.

show abstract

Micromixing in Reactive, Deformable Bubble and Droplet Swarms

Koynov

Khinast

2006

Chem Eng & Technol

View full text Add to dashboard Cite

Detailed, high-resolution numerical simulations have been performed of the buoyancy-driven motion of deformable, chemically reacting bubble and droplet swarms. Mass transfer rates and chemical reaction selectivities were determined and a comparison is presented between the results for bubble/droplet swarms and single bubbles. The mixing in the wake of bubbles was characterized as well. It was shown that for mixing-sensitive reaction networks, the hydrodynamics of the bubble swarm may significantly impact the reaction selectivity. Four special cases are highlighted, i.e., highly exothermic reactions, heterogeneously catalyzed reactions, animal cell cultures and experiments. The most important outcome of this work is that bubble swarms and the impact of the swarm hydrodynamics on reacting systems can be studied in detail. This is the first study of this kind reported in the literature. Its importance is paramount as knowledge of the unique flow dynamics inside bubble swarms is crucial to understanding the mechanisms controlling mass transport and chemical reactions and is a prerequisite for effective process intensification.

show abstract

The vortex-shedding process behind two-dimensional bluff bodies

Cited by 255 publications

References 3 publications

Experimental and numerical investigation of the vortex formation process behind a heated cylinder

Experimental and numerical investigation of the vortex formation process behind a heated cylinder

Codimension three bifurcation of streamline patterns close to a no-slip wall: A topological description of boundary layer eruption

Micromixing in Reactive, Deformable Bubble and Droplet Swarms

Contact Info

Product

Resources

About