A note on flow-induced force measurement of oscillating cylinder by loadcell

Alam, Md. Mahbub

doi:10.1016/j.oceaneng.2022.110538

Cited by 20 publications

(8 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is distinct from the frequency variation of a circular cylinder undergoing VIV at the same mass ratio 2.0, that is, the vibration frequency is close to its natural frequency in the lower branch (see the stars in figure 3 b ). It is worth noting that the excitation of large-amplitude vibration is not necessarily accompanied by the match of the vibration frequency and the natural frequency of a body in vacuum due to the added mass effects (Alam 2022). Williamson & Govardhan (2004) stated that light bodies can conceivably vibrate with large amplitudes at hundreds of times the natural frequency.…”

Section: Structural Responsesmentioning

confidence: 99%

Flow-induced vibrations of a D-section prism at a low Reynolds number

Chen

Alam

et al. 2022

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

This paper presents the response and the wake modes of a freely vibrating D-section prism with varying angles of attack ( $\alpha = 0^\circ \text {--}180^\circ$ ) and reduced velocity ( $U^* = 2\text {--}20$ ) by a numerical investigation. The Reynolds number, based on the effective diameter, is fixed at 100. The vibration of the prism is allowed only in the transverse direction. We found six types of response with increasing angle of attack: typical vortex-induced vibration (VIV) at $\alpha = 0^\circ \text {--}35^\circ$ ; extended VIV at $\alpha = 40^\circ \text {--}65^\circ$ ; combined VIV and galloping at $\alpha = 70^\circ \text {--}80^\circ$ ; narrowed VIV at $\alpha = 85^\circ \text {--}150^\circ$ ; transition response, from narrowed VIV to pure galloping, at $\alpha = 155^\circ \text {--}160^\circ$ ; and pure galloping at $\alpha = 165^\circ \text {--}180^\circ$ . The typical and narrowed VIVs are characterized by linearly increasing normalized vibration frequency with increasing $U^*$ , which is attributed to the stationary separation points of the boundary layer. On the other hand, in the extended VIV, the vortex shedding frequency matches the natural frequency in a large $U^*$ range with increasing $\alpha$ generally. The galloping is characterized by monotonically increasing amplitude with enlarging $U^*$ , with the largest amplitude being $A^* = 3.2$ . For the combined VIV and galloping, the vibration amplitude is marginal in the VIV branch while it significantly increases with $U^*$ in the galloping branch. In the transition from narrowed VIV to pure galloping, the vibration frequency shows a galloping-like feature, but the amplitude does not monotonically increase with increasing $U^*$ . Moreover, a partition of the wake modes in the $U^*$ – $\alpha$ parametric plane is presented, and the flow physics is elucidated through time variations of the displacement, drag and lift coefficients and vortex dynamics. The angle-of-attack range of galloping is largely predicted by performing a quasi-steady analysis of the galloping instability. Finally, the effects of $m^*$ and ${\textit {Re}}$ , the roles of afterbody and the roles of separation point in determining vibration responses and vortex shedding frequency are further discussed.

show abstract

Section: Structural Responsesmentioning

confidence: 99%

Flow-induced vibrations of a D-section prism at a low Reynolds number

Chen

Alam

et al. 2022

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In our paper, the effective added mass is calculated from the component of the fluid force in phase with the foil acceleration ((3.7)–(3.9)). The effective added mass includes both potential added mass and flow-induced added mass (Konstantinidis, Dorogi & Baranyi 2021; Alam 2022). As a result, the effective added mass can be positive or negative, as shown in figure 14( b 1).…”

Section: Resultsmentioning

confidence: 99%

Hydrodynamic performance of slender swimmer: effect of travelling wavelength

2022

View full text Add to dashboard Cite

The impact of Strouhal number St (= 0.1–1.0), Reynolds number Re (= 50–2000) and dimensionless wavelength λ (= 0.5–2.0) on the hydrodynamic performance of a travelling wavy foil of a constant length is extensively investigated. The relationship of time-mean thrust with St, Re and λ is presented, suggesting that the propulsive force increases with increasing St, Re and λ. As such, the drag–thrust boundary advances as these parameters increase. A shorter λ makes the thrust steadier while a longer λ enhances the maximum instantaneous thrust. The latter is beneficial for prey to escape from a predator. The fluid added mass caused by the foil oscillation increases with St and λ but declines with Re (<500). Seven types of wake structures produced by the foil are identified, discussed and connected to thrust generation, showing how St, Re and λ affect the fluid dynamics, wake transition, vortex strength, wake jet, velocity, added mass, added damping, power input, efficiency and pressure profiles. The outcome of this work renders a physical basis for understanding the swimming of aquatic animals.

show abstract

“…According to Lighthill (1986), the lift force ( F L ) can be decomposed into a ‘potential force’ component and a ‘vortex force’ component, where the ‘potential force’ is caused by the potential added-mass force and the ‘vortex force’ is due to the dynamics of vorticity in the flow. Given that the fluid is viscous, Alam (2022) proposed a quiescent-fluid added-mass force F La 0 (replacing the potential force) and a flow-induced force F Lf (replacing the vortex force). Naturally, the magnitude of the quiescent-fluid added-mass force differs from that of the potential force, depending on the body shapes and orientations (Chen, Alam & Zhou 2020).…”

Section: Resultsmentioning

confidence: 99%

“…When f nf is measured directly from the decay of the cylinder oscillation, all the parameters on the right-hand side of (3.7) are known, which leads to the estimation of m a . See Chen et al (2020) and Alam (2022) for details of measuring m a . The quiescent-fluid added-mass coefficient m * a0 is coincidentally about 1.0 for a circular cylinder but approximately 1.5 for a square cylinder with zero incidence angle (Chen et al 2020).…”

Section: Quiescent Fluid Added-mass Force and Flow-induced Forcementioning

confidence: 99%

Intrinsic features of flow-induced stability of a square cylinder

Lin,

Alam

2024

J. Fluid Mech.

Self Cite

View full text Add to dashboard Cite

Vortex-induced vibrations and galloping of an elastically mounted square cylinder are investigated for cylinder mass ratio m* = 2–50, damping ratio ζ = 0–1.0, mass-damping ratio m*ζ = 0–50 and flow reduced velocity Ur = 1–80. We home in on the effects of m*, ζ, m*ζ, $({m^\ast } + m_{a\textrm{0}}^\ast )\zeta$ and $({m^\ast } + m_{ae}^\ast )\zeta$ on the critical reduced velocity Urc marking the onset of galloping, where $m_{a\textrm{0}}^\ast $ is the quiescent-fluid added mass ratio and $m_{ae}^\ast $ is the effective added mass ratio. Vibration responses, forces, vibration frequencies and added mass ratios are studied and discussed. The different branches of vortex-induced vibrations have different dependencies of $m_{ae}^\ast $ on Ur. The $m_{ae}^\ast $ in the initial branch is positive and drops rapidly with Ur, but that in the lower branch is negative and declines gently. In the galloping regime, $m_{ae}^\ast $ jumps from negative to positive at the onset of galloping, declining slightly with increasing Ur. Our results and prediction equations show that when ζ = 0, Urc is independent of m* for m* ≥ 5, albeit slightly higher for m* = 3. The latter is ascribed to mode competition. When ζ > 0, Urc linearly increases with increasing ζ. Detailed analysis substantiates that m*ζ or $({m^\ast } + m_{a\textrm{0}}^\ast )\zeta$ does not serve as the unique criterion to predict the galloping occurrence. Here, we propose a new combined mass-damping parameter $({m^\ast } + m_{ae}^\ast )\zeta$ in the relationship between galloping onsets and structural properties, which successfully scales all data of Urc at different m* and ζ values.

show abstract

A note on flow-induced force measurement of oscillating cylinder by loadcell

Cited by 20 publications

References 38 publications

Flow-induced vibrations of a D-section prism at a low Reynolds number

Flow-induced vibrations of a D-section prism at a low Reynolds number

Hydrodynamic performance of slender swimmer: effect of travelling wavelength

Intrinsic features of flow-induced stability of a square cylinder

Contact Info

Product

Resources

About