Three-dimensional direct numerical simulation of wake transitions of a circular cylinder

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Abstract

© 2016 Cambridge University Press.
This paper presents three-dimensional (3D) direct numerical simulations (DNS) of flow past a circular cylinder over a range of Reynolds number up to 300. The gradual wake transition process from mode A∗ (i.e. mode A with large-scale vortex dislocations) to mode B is well captured over a range of Re from 230 to 260. The mode swapping process is investigated in detail with the aid of numerical flow visualization. It is found that the mode B structures in the transition process are developed based on the streamwise vortices of mode A or A∗ which destabilize the braid shear layer region. For each case within the transition range, the transient mode swapping process consists of dislocation and non-dislocation cycles. With the increase of Re, it becomes more difficult to trigger dislocations from the pure mode A structure and form a dislocation cycle, and each dislocation stage becomes shorter in duration, resulting in a continuous decrease in the probability of occurrence of mode A∗ and a continuous increase in the probability of occurrence of mode B. The occurrence of mode A∗ results in a relatively strong flow three-dimensionality. A critical condition is confirmed at approximately Re = 265-270, where the weakest flow three-dimensionality is observed, marking a transition from the disappearance of mode A∗ to the emergence of increasingly disordered mode B structures.
Original languageEnglish
Pages (from-to)353-391
JournalJournal of Fluid Mechanics
Volume801
Early online date25 Jul 2016
DOIs
Publication statusPublished - Aug 2016

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Direct numerical simulation
circular cylinders
Circular cylinders
direct numerical simulation
wakes
Vortex flow
Flow visualization
Reynolds number
occurrences
numerical flow visualization
vortices
cycles
shear layers
marking
actuators

Cite this

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title = "Three-dimensional direct numerical simulation of wake transitions of a circular cylinder",
abstract = "{\circledC} 2016 Cambridge University Press.This paper presents three-dimensional (3D) direct numerical simulations (DNS) of flow past a circular cylinder over a range of Reynolds number up to 300. The gradual wake transition process from mode A∗ (i.e. mode A with large-scale vortex dislocations) to mode B is well captured over a range of Re from 230 to 260. The mode swapping process is investigated in detail with the aid of numerical flow visualization. It is found that the mode B structures in the transition process are developed based on the streamwise vortices of mode A or A∗ which destabilize the braid shear layer region. For each case within the transition range, the transient mode swapping process consists of dislocation and non-dislocation cycles. With the increase of Re, it becomes more difficult to trigger dislocations from the pure mode A structure and form a dislocation cycle, and each dislocation stage becomes shorter in duration, resulting in a continuous decrease in the probability of occurrence of mode A∗ and a continuous increase in the probability of occurrence of mode B. The occurrence of mode A∗ results in a relatively strong flow three-dimensionality. A critical condition is confirmed at approximately Re = 265-270, where the weakest flow three-dimensionality is observed, marking a transition from the disappearance of mode A∗ to the emergence of increasingly disordered mode B structures.",
author = "Hongyi Jiang and Liang Cheng and Scott Draper and Hongwei An and Feifei Tong",
year = "2016",
month = "8",
doi = "10.1017/jfm.2016.446",
language = "English",
volume = "801",
pages = "353--391",
journal = "Journal of Fluid Mechanics.",
issn = "0022-1120",
publisher = "Cambridge University Press",

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T1 - Three-dimensional direct numerical simulation of wake transitions of a circular cylinder

AU - Jiang, Hongyi

AU - Cheng, Liang

AU - Draper, Scott

AU - An, Hongwei

AU - Tong, Feifei

PY - 2016/8

Y1 - 2016/8

N2 - © 2016 Cambridge University Press.This paper presents three-dimensional (3D) direct numerical simulations (DNS) of flow past a circular cylinder over a range of Reynolds number up to 300. The gradual wake transition process from mode A∗ (i.e. mode A with large-scale vortex dislocations) to mode B is well captured over a range of Re from 230 to 260. The mode swapping process is investigated in detail with the aid of numerical flow visualization. It is found that the mode B structures in the transition process are developed based on the streamwise vortices of mode A or A∗ which destabilize the braid shear layer region. For each case within the transition range, the transient mode swapping process consists of dislocation and non-dislocation cycles. With the increase of Re, it becomes more difficult to trigger dislocations from the pure mode A structure and form a dislocation cycle, and each dislocation stage becomes shorter in duration, resulting in a continuous decrease in the probability of occurrence of mode A∗ and a continuous increase in the probability of occurrence of mode B. The occurrence of mode A∗ results in a relatively strong flow three-dimensionality. A critical condition is confirmed at approximately Re = 265-270, where the weakest flow three-dimensionality is observed, marking a transition from the disappearance of mode A∗ to the emergence of increasingly disordered mode B structures.

AB - © 2016 Cambridge University Press.This paper presents three-dimensional (3D) direct numerical simulations (DNS) of flow past a circular cylinder over a range of Reynolds number up to 300. The gradual wake transition process from mode A∗ (i.e. mode A with large-scale vortex dislocations) to mode B is well captured over a range of Re from 230 to 260. The mode swapping process is investigated in detail with the aid of numerical flow visualization. It is found that the mode B structures in the transition process are developed based on the streamwise vortices of mode A or A∗ which destabilize the braid shear layer region. For each case within the transition range, the transient mode swapping process consists of dislocation and non-dislocation cycles. With the increase of Re, it becomes more difficult to trigger dislocations from the pure mode A structure and form a dislocation cycle, and each dislocation stage becomes shorter in duration, resulting in a continuous decrease in the probability of occurrence of mode A∗ and a continuous increase in the probability of occurrence of mode B. The occurrence of mode A∗ results in a relatively strong flow three-dimensionality. A critical condition is confirmed at approximately Re = 265-270, where the weakest flow three-dimensionality is observed, marking a transition from the disappearance of mode A∗ to the emergence of increasingly disordered mode B structures.

U2 - 10.1017/jfm.2016.446

DO - 10.1017/jfm.2016.446

M3 - Article

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EP - 391

JO - Journal of Fluid Mechanics.

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ER -