Abstract
In this paper, flow over a streamwise oscillating circular cylinder is numerically simulated to examine the effects of the driving amplitude and frequency on the distribution of the lock-in regions in laminar flows. At , lock-in is categorized according to the spectral features of the lift coefficient as two different lock-in phenomena: Harmonic and subharmonic lock-in. These lock-in phenomena are represented as maps on the driving amplitude-frequency plane, which have subharmonic lock-in regions and two harmonic lock-in regions. The frequency range of the subharmonic region is shifted to lower frequencies with increasing amplitude, and the lower boundary of this subharmonic region is successfully predicted. A symmetric harmonic region with a symmetric vortex pattern is observed in a certain velocity range for a moving cylinder. Aerodynamic features induced by different flow patterns in each region are presented on the driving amplitude-frequency plane. The lock-in region and aerodynamic features at and are compared with the results for . A subharmonic region and two harmonic regions are observed at , and these show the same features as for at a low driving amplitude. Lock-in at also shows one subharmonic region and two harmonic regions. However, compared with the case, the symmetric harmonic lock-in is dominant. The features of aerodynamic force at and are represented on a force map, which shows similar characteristics in corresponding regions for the case.
| Original language | English |
|---|---|
| Pages (from-to) | 315-351 |
| Number of pages | 37 |
| Journal | Journal of Fluid Mechanics |
| Volume | 858 |
| DOIs | |
| Publication status | Published - 2019 Jan 10 |
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All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
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Lock-in regions of laminar flows over a streamwise oscillating circular cylinder. / Kim, Ki Ha; Choi, Jung Il.
In: Journal of Fluid Mechanics, Vol. 858, 10.01.2019, p. 315-351.Research output: Contribution to journal › Article
TY - JOUR
T1 - Lock-in regions of laminar flows over a streamwise oscillating circular cylinder
AU - Kim, Ki Ha
AU - Choi, Jung Il
PY - 2019/1/10
Y1 - 2019/1/10
N2 - In this paper, flow over a streamwise oscillating circular cylinder is numerically simulated to examine the effects of the driving amplitude and frequency on the distribution of the lock-in regions in laminar flows. At , lock-in is categorized according to the spectral features of the lift coefficient as two different lock-in phenomena: Harmonic and subharmonic lock-in. These lock-in phenomena are represented as maps on the driving amplitude-frequency plane, which have subharmonic lock-in regions and two harmonic lock-in regions. The frequency range of the subharmonic region is shifted to lower frequencies with increasing amplitude, and the lower boundary of this subharmonic region is successfully predicted. A symmetric harmonic region with a symmetric vortex pattern is observed in a certain velocity range for a moving cylinder. Aerodynamic features induced by different flow patterns in each region are presented on the driving amplitude-frequency plane. The lock-in region and aerodynamic features at and are compared with the results for . A subharmonic region and two harmonic regions are observed at , and these show the same features as for at a low driving amplitude. Lock-in at also shows one subharmonic region and two harmonic regions. However, compared with the case, the symmetric harmonic lock-in is dominant. The features of aerodynamic force at and are represented on a force map, which shows similar characteristics in corresponding regions for the case.
AB - In this paper, flow over a streamwise oscillating circular cylinder is numerically simulated to examine the effects of the driving amplitude and frequency on the distribution of the lock-in regions in laminar flows. At , lock-in is categorized according to the spectral features of the lift coefficient as two different lock-in phenomena: Harmonic and subharmonic lock-in. These lock-in phenomena are represented as maps on the driving amplitude-frequency plane, which have subharmonic lock-in regions and two harmonic lock-in regions. The frequency range of the subharmonic region is shifted to lower frequencies with increasing amplitude, and the lower boundary of this subharmonic region is successfully predicted. A symmetric harmonic region with a symmetric vortex pattern is observed in a certain velocity range for a moving cylinder. Aerodynamic features induced by different flow patterns in each region are presented on the driving amplitude-frequency plane. The lock-in region and aerodynamic features at and are compared with the results for . A subharmonic region and two harmonic regions are observed at , and these show the same features as for at a low driving amplitude. Lock-in at also shows one subharmonic region and two harmonic regions. However, compared with the case, the symmetric harmonic lock-in is dominant. The features of aerodynamic force at and are represented on a force map, which shows similar characteristics in corresponding regions for the case.
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U2 - 10.1017/jfm.2018.787
DO - 10.1017/jfm.2018.787
M3 - Article
AN - SCOPUS:85056287357
VL - 858
SP - 315
EP - 351
JO - Journal of Fluid Mechanics
JF - Journal of Fluid Mechanics
SN - 0022-1120
ER -