Numerical investigation of fluid resonance in two narrow gaps of three identical rectangular structures

Lü, Lin; Cheng, Liang; Teng, Bin; Zhao, Ming

doi:10.1016/j.apor.2009.10.003

Cited by 93 publications

(31 citation statements)

References 16 publications

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“…Reported results (e.g. Lu et al [14], [15], [16], [12]; Sauder et al [17], Moradi et al [18]) have shown satisfactory agreement with those obtained from experiments, indicating that the viscous fluid model performs well in predicting the violent free surface oscillation at the fluid resonance. The effects of different parameters, such as body draft, gap width and body breadth on resonant characteristics in side-by-side offloading operations were also studied by Saitoh e al.…”

Section: Introductionmentioning

confidence: 73%

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Two-dimensional numerical study on the effect of water depth on resonance behaviour of the fluid trapped between two side-by-side bodies

Moradi

Zhou

Cheng

2016

Applied Ocean Research

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The effect of water depth on gap resonance of two side-by-side rectangular boxes is examined in a 2D numerical wave flume at various gap widths and body drafts. The numerical model used is based on the volume of fluid (VOF) method for the solution of Navier-Stokes equations combined with free surfaces. The water depth covered ranges from shallow to deep water regimes. It is found that the resonant frequencies and wave heights show apparent dependence on water depth. For a given body draft and gap width, the resonant wave frequency shifts to higher values whereas the resonant wave height inside the gap decreases as water depth increases. The amount of reduction of wave height is found to be dependent on the depth to draft and gap width to breadth ratio. It is observed that the effect of water depth on resonance frequency is very small when the ratio of water depth to body draft is equal to or greater than six, while the effect of water depth on resonant water level diminishes when this ratio increases beyond 10. Furthermore, it is observed that the variation trends of the resonant frequency and the reduction of the resonant wave height with water depth are similar at different drafts and gap widths. The present results suggest that the water depth, body draft and the ratio of water depth to body draft are the key factors that influence the resonant responses. It is also found that the potential flow model not only over-predicts the resonant wave heights but also fails to predict the variation trends of the resonant wave height with water depth.

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Section: Introductionmentioning

confidence: 73%

“…The bodies have a bottom clearance of h-d. The incoming wave height H 0 is fixed at 0.024 m and the wave length L varies between 1 m and 6.28 m. These values are similar to those used in Saitoh et al [19], Lu et al [15] and Moradi et al [18].…”

Section: Numerical Model Setup and Boundary Conditionsmentioning

confidence: 97%

Two-dimensional numerical study on the effect of water depth on resonance behaviour of the fluid trapped between two side-by-side bodies

Moradi

Zhou

Cheng

2016

Applied Ocean Research

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“…While the widely used velocity extrapolations [33,34] are incorporated in the present viscous numerical wave flume. The mesh resolution and time step dependence associated with the present viscous numerical model has been verified carefully in our previous work [24][25][26]. In general, the total number of meshes used in this work are generally more than 100000 with the smallest grid size of B g /20 × B g /20 in the narrow gaps, where B g is the gap width.…”

Section: Viscous Fluid Modelmentioning

confidence: 98%

“…A straightforward manner to develop such a numerical model is to adopt the fundamental Navier-Stokes equations to describe the actual viscous fluid flow. However, the performance of the viscous fluid model equipped with free surface capture technique to simulate violent wave oscillation in narrow gaps are shown to be very time-consuming although it is able to produce indeed the satisfying numerical results as expected [24][25][26]. The main purpose of this work is to investigate the problem of fluid resonance in narrow gaps using both the viscous fluid model and the potential flow model.…”

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confidence: 99%

Modelling of multi-bodies in close proximity under water waves—Fluid resonance in narrow gaps

Lü

Teng

Cheng

et al. 2010

Sci. China Phys. Mech. Astron.

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f = −μV, μ the damping coefficient and V the local averaging flow velocity) are employed in this work to investigate the phenomenon of fluid resonance in narrow gaps between multi-bodies in close proximity under water waves. The numerical results are compared with experimental data available in the literature. The comparison demonstrates that both the viscous fluid model and the potential flow model are able to predict the resonant frequency reasonably well. However the conventional potential flow model (without artificial damping term) significantly over-predicts the wave height in narrow gaps around the resonant frequency. In order to calibrate the appropriate damping coefficient used for the potential model and make it work as well as the viscous fluid model in predicting the resonant wave height in narrow gaps but with little computational efforts, the dependence of damping coefficient μ on the body geometric dimensions is examined considering the parameters of gap width B g , body draft D, body breadth ratio B r and body number n (n = 2, 3), where B r = B B /B A for the case of two bodies (Body A and Body B) with different breadths of B A and B B , respectively. It was confirmed that the damping coefficient used for the potential flow model is not sensitive to the geometric dimensions and spatial arrangement. It was found that μ ∈ [0.4, 0.5] may guarantee the variation of H g /H 0 with kh to be generally in good agreement with the experimental data and the results of viscous fluid model, where H g is the excited wave height in narrow gaps under various dimensionless incident wave frequencies kh, H 0 is the incident wave height, k = 2π/L is the wave number and h is the water depth. narrow gap, fluid resonance, water wave, viscous fluid model, potential flow model, finite element method, boundary element method

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“…By using two-dimensional potential and viscous flow methods, Lu et al [2] studied the wave amplitude inside narrow gaps between three adjacent boxes subjected to incoming waves. Model tests and numerical calculations in three dimensions of the gap resonance between two rigidly linked side-by-side barges were performed by Molin et al [3].…”

Section: Introductionmentioning

confidence: 99%

Wave-induced response of a floating two-dimensional body with a moonpool

Fredriksen¹,

Kristiansen²,

Faltinsen

2015

Phil. Trans. R. Soc. A.

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Regular wave-induced behaviour of a floating stationary two-dimensional body with a moonpool is studied. The focus is on resonant piston-mode motion in the moonpool and rigid-body motions. Dedicated two-dimensional experiments have been performed. Two numerical hybrid methods, which have previously been applied to related problems, are further developed. Both numerical methods couple potential and viscous flow. The semi-nonlinear hybrid method uses linear free-surface and body-boundary conditions. The other one uses fully nonlinear free-surface and body-boundary conditions. The harmonic polynomial cell method solves the Laplace equation in the potential flow domain, while the finite volume method solves the Navier–Stokes equations in the viscous flow domain near the body. Results from the two codes are compared with the experimental data. The nonlinear hybrid method compares well with the data, while certain discrepancies are observed for the semi-nonlinear method. In particular, the roll motion is over-predicted by the semi-nonlinear hybrid method. Error sources in the semi-nonlinear hybrid method are discussed. The moonpool strongly affects heave motions in a frequency range around the piston-mode resonance frequency of the moonpool. No resonant water motions occur in the moonpool at the piston-mode resonance frequency. Instead large moonpool motions occur at a heave natural frequency associated with small damping near the piston-mode resonance frequency.

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Numerical investigation of fluid resonance in two narrow gaps of three identical rectangular structures

Cited by 93 publications

References 16 publications

Two-dimensional numerical study on the effect of water depth on resonance behaviour of the fluid trapped between two side-by-side bodies

Two-dimensional numerical study on the effect of water depth on resonance behaviour of the fluid trapped between two side-by-side bodies

Modelling of multi-bodies in close proximity under water waves—Fluid resonance in narrow gaps

Wave-induced response of a floating two-dimensional body with a moonpool

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