### Abstract

This study reports on an experimental investigation of the effect of mass ratio on the transverse flow-induced vibration (FIV) response of an elastically mounted square cylinder placed at three different incidence angles: two symmetric with respect to the centreplane, α=0° and 45°; and one asymmetric at 20°. These three angles display different dominant FIV phenomena: transverse galloping and combined vortex-induced vibration (VIV) and galloping for α=0°, VIV for α=45°, and higher branch subharmonic (period-doubled) VIV for α=20° (Nemes et al., 2012). The mass ratio is defined as the ratio of the total oscillating mass (m) to the displaced fluid mass (m
_{d}
), m
^{∗}
=m∕m
_{d}
. The present results show that the mass ratio (m
^{∗}
=2.64 – 15.00) has a significant influence on the structural vibration response for all FIV phenomena, and can dictate whether two of these modes exist at all. Three primary observations are presented: for the α=0° case, the combined VIV–galloping response is diminished as the mass ratio is increased, and it ceases to exist for m
^{∗}
⩾11.31; for the α=45° case, the peak values of the normalised oscillation amplitude during VIV are only reduced marginally with increasing m
^{∗}
, however the body oscillation amplitude in the desynchronised regions is significantly attenuated; for the α=20° case, there exists a critical mass ratio (m
_{crit}
^{∗}
≃3.50) above which the higher branch subharmonic VIV does not persist.

Original language | English |
---|---|

Pages (from-to) | 200-212 |

Number of pages | 13 |

Journal | Journal of Fluids and Structures |

Volume | 86 |

DOIs | |

Publication status | Published - 1 Apr 2019 |

### Keywords

- Flow-induced vibration
- Fluid–structure interaction
- Square cylinder

### Cite this

}

*Journal of Fluids and Structures*, vol. 86, pp. 200-212. https://doi.org/10.1016/j.jfluidstructs.2019.02.008

**The effect of mass ratio on the structural response of a freely vibrating square cylinder oriented at different angles of attack.** / Zhao, Jisheng; Leontini, Justin; Lo Jacono, David; Sheridan, John.

Research output: Contribution to journal › Article › Research › peer-review

TY - JOUR

T1 - The effect of mass ratio on the structural response of a freely vibrating square cylinder oriented at different angles of attack

AU - Zhao, Jisheng

AU - Leontini, Justin

AU - Lo Jacono, David

AU - Sheridan, John

PY - 2019/4/1

Y1 - 2019/4/1

N2 - This study reports on an experimental investigation of the effect of mass ratio on the transverse flow-induced vibration (FIV) response of an elastically mounted square cylinder placed at three different incidence angles: two symmetric with respect to the centreplane, α=0° and 45°; and one asymmetric at 20°. These three angles display different dominant FIV phenomena: transverse galloping and combined vortex-induced vibration (VIV) and galloping for α=0°, VIV for α=45°, and higher branch subharmonic (period-doubled) VIV for α=20° (Nemes et al., 2012). The mass ratio is defined as the ratio of the total oscillating mass (m) to the displaced fluid mass (m d ), m ∗ =m∕m d . The present results show that the mass ratio (m ∗ =2.64 – 15.00) has a significant influence on the structural vibration response for all FIV phenomena, and can dictate whether two of these modes exist at all. Three primary observations are presented: for the α=0° case, the combined VIV–galloping response is diminished as the mass ratio is increased, and it ceases to exist for m ∗ ⩾11.31; for the α=45° case, the peak values of the normalised oscillation amplitude during VIV are only reduced marginally with increasing m ∗ , however the body oscillation amplitude in the desynchronised regions is significantly attenuated; for the α=20° case, there exists a critical mass ratio (m crit ∗ ≃3.50) above which the higher branch subharmonic VIV does not persist.

AB - This study reports on an experimental investigation of the effect of mass ratio on the transverse flow-induced vibration (FIV) response of an elastically mounted square cylinder placed at three different incidence angles: two symmetric with respect to the centreplane, α=0° and 45°; and one asymmetric at 20°. These three angles display different dominant FIV phenomena: transverse galloping and combined vortex-induced vibration (VIV) and galloping for α=0°, VIV for α=45°, and higher branch subharmonic (period-doubled) VIV for α=20° (Nemes et al., 2012). The mass ratio is defined as the ratio of the total oscillating mass (m) to the displaced fluid mass (m d ), m ∗ =m∕m d . The present results show that the mass ratio (m ∗ =2.64 – 15.00) has a significant influence on the structural vibration response for all FIV phenomena, and can dictate whether two of these modes exist at all. Three primary observations are presented: for the α=0° case, the combined VIV–galloping response is diminished as the mass ratio is increased, and it ceases to exist for m ∗ ⩾11.31; for the α=45° case, the peak values of the normalised oscillation amplitude during VIV are only reduced marginally with increasing m ∗ , however the body oscillation amplitude in the desynchronised regions is significantly attenuated; for the α=20° case, there exists a critical mass ratio (m crit ∗ ≃3.50) above which the higher branch subharmonic VIV does not persist.

KW - Flow-induced vibration

KW - Fluid–structure interaction

KW - Square cylinder

UR - http://www.scopus.com/inward/record.url?scp=85062145169&partnerID=8YFLogxK

U2 - 10.1016/j.jfluidstructs.2019.02.008

DO - 10.1016/j.jfluidstructs.2019.02.008

M3 - Article

VL - 86

SP - 200

EP - 212

JO - Journal of Fluids and Structures

JF - Journal of Fluids and Structures

SN - 0889-9746

ER -