Wake behind a concave curved cylinder

Jiang, Fengjian; Pettersen, Bjørnar; Andersson, Helge I.; Kim, Jongmin; Kim, Sung-Tae

doi:10.1103/physrevfluids.3.094804

Cited by 12 publications

(52 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Jiang et al. (2018 b ) also reported the existence of multiple flow regimes in the concave curved cylinder wake, which agrees with the experimental observations in Shang et al. (2018).…”

Section: Introductionsupporting

confidence: 84%

“…The main features of this wake flow, as learned from earlier low- investigations (see Jiang et al. 2018 b ; Shang et al. 2018) are also sketched.…”

Section: Mathematical Modelling and Computational Issuesmentioning

confidence: 76%

“…A general trend is that the effect of is reduced as increases (see figure 11 in Jiang et al. (2018 b )), which is favourable for higher- DNS on account of the computational cost. However, there is no a priori experience on the effect at .…”

Section: Introductionmentioning

confidence: 91%

“…As an advantage in numerical set-ups, Jiang et al. (2018 b ) could freely vary the vertical extension length. This further allowed them to study the frequency variation along the curved cylinder span, and revealed various types of frequency variation over a relatively small range.…”

Section: Introductionmentioning

confidence: 99%

“…Jiang et al. (2018 b ) showed that the magnitude of the axial velocity behind a concave curved cylinder can be comparable to the inflow velocity, at . Such prominent axial flow may prevent the interaction between the free shear layers shed from the two sides of the cylinder and act equivalently to a splitter plate.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Turbulent wake behind a concave curved cylinder

2019

Self Cite

View full text Add to dashboard Cite

We present a detailed study of the turbulent wake behind a quarter-ring curved cylinder at Reynolds number $Re=3900$ (based on cylinder diameter and incoming flow velocity), by means of direct numerical simulation. The configuration is referred to as a concave curved cylinder with incoming flow aligned with the plane of curvature and towards the inner face of the cylinder. Wake flows behind this configuration are known to be complex, but have so far only been studied at low $Re$. This is the first direct numerical simulation investigation of the turbulent wake behind the concave configuration, from which we reveal new and interesting wake dynamics, and present in-depth physical interpretations. Similar to the low-$Re$ cases, the turbulent wake behind a concave curved cylinder is a multi-regime and multi-frequency flow. However, in addition to the coexisting flow regimes reported at lower $Re$, we observe a new transitional flow regime at $Re=3900$. The flow field in this transitional regime is dominated not by von Kármán-type vortex shedding, but by periodic asymmetric helical vortices. Such vortex pairs exist also in some other wake flows, but are then non-periodic. Inspections reveal that the periodic motion of the asymmetric helical vortices is induced by vortex shedding in its neighbouring oblique shedding regime. The oblique shedding regime is in turn influenced by the transitional regime, resulting in a unified and remarkably low dominating frequency in both flow regimes. Owing to this synchronized frequency, the new wake dynamics in the transitional regime might easily be overlooked. In the near wake, two distinct peaks are observed in the time-averaged axial velocity distribution along the curved cylinder span, while only one peak was observed at lower $Re$. The presence of the additional peak is ascribed to a strong favourable base pressure gradient along the cylinder span. It is noteworthy that the axially directed base flow exceeded the incoming velocity behind a substantial part of the quarter-ring and even persisted upwards along the straight vertical extension. As a by-product of our study, we find that a straight vertical extension of 16 cylinder diameters is required in order to avoid any adverse effects from the upper boundary of the flow domain.

show abstract

“…Jiang et al. (2018 b ) also reported the existence of multiple flow regimes in the concave curved cylinder wake, which agrees with the experimental observations in Shang et al. (2018).…”

Section: Introductionsupporting

confidence: 84%

“…The main features of this wake flow, as learned from earlier low- investigations (see Jiang et al. 2018 b ; Shang et al. 2018) are also sketched.…”

Section: Mathematical Modelling and Computational Issuesmentioning

confidence: 76%