scholarly journals Solitary Wave Diffraction with a Single and Two Vertical Circular Cylinders

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zouhair Hafsia ◽  
Saliha Nouri ◽  
Salah Mahmoud Boulaaras ◽  
Ali Allahem ◽  
Salem Alkhalaf ◽  
...  
Keyword(s):  
Solitary Wave ◽  
Wave Diffraction ◽  
Present Model ◽  
Three Dimensional ◽  
Wave Generation ◽  
Transport Equations ◽  
Circular Cylinders ◽  
Wave Crest ◽  
Wave Flow ◽  
Wave Forces

This study investigates the three-dimensional (3-D) solitary wave interaction with two cylinders in tandem and side-by-side arrangements for two wave heights. The solitary wave generation and propagation are predicted using the volume of fluid method (VOF) coupled with the NavierStokes transport equations. The PHOENICS code is used to solve these transport equations. The solitary wave generation based on the source line developed by Hafsia et al. (2009) is extended in three-dimensional wave flow and is firstly validated for solitary waves propagating on a flat bottom. The comparison between numerical results and analytical solution for small wave height H / h = 0.1 and 0.2 shows good agreements. The wave crest and the pseudo-wavelength are well reproduced. Excellent agreements were found in terms of maximum run-up and wave forces by comparison with the present model and analytical studies. The present model can be tested for the extreme solitary wave to extend its application to a more realistic case study as the solitary wave diffraction with an offshore oil platform.

scholarly journals Three-Dimensional Simulations of Offshore Oil Platform in Square and Diamond Arrangements

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Saliha Nouri ◽  
Zouhair Hafsia ◽  
Salah Mahmoud Boulaaras ◽  
Ali Allahem ◽  
Salem Alkhalaf ◽  
...  
Keyword(s):  
Solitary Wave ◽  
Three Dimensional ◽  
Wave Force ◽  
Circular Cylinders ◽  
Shielding Effect ◽  
Wave Crest ◽  
Wave Flow ◽  
Internal Source ◽  
Flat Bottom ◽  
Surface Evolution

The interaction of the solitary wave with an oil platform composed of four vertical circular cylinders is investigated for two attack angle of the solitary wave β = 0 ° (square arrangement) and β = 45 ° (diamond arrangement). The solitary wave is generated using an internal source line as proposed by Hafsia et al. (2009). This generation method is extended to three-dimensional wave flow and is integrated into the PHOENICS code. The volume of fluid approach is used to capture the free surface evolution. The present model is validated in the case of a solitary wave propagating on a flat bottom for H / h = 0.25 where H is the wave height and h is the water depth. Compared to the analytical solution, the pseudowavelength and the wave crest are well reproduced. For a solitary wave interacting with square and diamond cylinders, the simulated results show that the maximum run-ups are well reproduced. For the diamond arrangements, the diffraction process seems to not affect the maximum run-ups, which approached the isolated cylinder. For the square arrangement, the shielding effect leads to a maximum wave force more pronounced for the upstream cylinder array.

Secondary and tertiary excitation of three-dimensional patterns on a falling film

1994 ◽  
Vol 270 ◽  
pp. 251-276 ◽  
Author(s):  
H.-C. Chang ◽  
M. Cheng ◽  
E. A. Demekhin ◽  
D. I. Kopelevich
Keyword(s):  
Solitary Wave ◽  
Three Dimensional ◽  
Wave Structure ◽  
Stationary Wave ◽  
Wave Crest ◽  
Checkerboard Pattern ◽  
Secondary Transition ◽  
Falling Film ◽  
Two Dimensional ◽  
Primary Instability

The primary instability of a falling film selectively amplifies two-dimensional noise down-stream over three-dimensional modes with transverse variation. If the initial three-dimensional noise is weak or if it has short wavelengths such that they are effectively damped by the capillary mechanism of the primary instability, our earlier study (Chang et al. 1993a) showed that the primary instability leads to a weakly nonlinear, nearly sinusoidal γ1 stationary wave which then undergoes a secondary transition to a strongly nonlinear γ2 wave with a solitary wave structure. We show here that the primary transition remains in the presence of significant three-dimensional noise but the secondary transition can be replaced by a selective excitation of oblique triad waves which can even include stable primary disturbances. The resulting secondary checkerboard pattern is associated with a subharmonic mode in the streamwise direction. If the initial transverse noise level is low, a secondary transition to a two-dimensional γ2 solitary wave is followed by a tertiary ‘phase instability’ dominated by transverse wave crest modulations.

scholarly journals Interaction of a Solitary Wave with Vertical Fully/Partially Submerged Circular Cylinders with/without a Hollow Zone

2020 ◽  
Vol 8 (12) ◽  
pp. 1022
Author(s):  
Chih-Hua Chang
Keyword(s):  
Circular Cylinder ◽  
Solitary Wave ◽  
Three Dimensional ◽  
Vertical Cylinder ◽  
Wave Model ◽  
Circular Cylinders ◽  
Cylinder Surface ◽  
Wave Elevation ◽  
Curvilinear Grid ◽  
Nonlinear Potential

In this article, a three-dimensional, fully nonlinear potential wave model is applied based on a curvilinear grid system. This model calculates the wave action on a fully/partially submerged vertical cylinder with or without a hollow zone. As basic verification, a solitary wave hitting a single fully or partially submerged circular cylinder is tested, and our numerical results agree with the experimental results obtained by others. The influence of cylinder immersion depth and size on the wave elevation change on the cylinder surface is considered. The model is also applied to investigate the wave energy of a solitary wave passing through a hollow circular cylinder to determine the effect of the size and draft on the wave oscillating in the hollow zone.

Experimental Investigation on the Role of Entrapped Air on Solitary Wave Forces on a Coastal Bridge Deck

2014 ◽  
Author(s):  
Betsy Seiffert ◽  
R. Cengiz Ertekin ◽  
Ian N. Robertson
Keyword(s):  
Solitary Wave ◽  
Water Surface ◽  
Wave Flow ◽  
Wave Forces ◽  
Qualitative Comparison ◽  
Wave Parameters ◽  
Bridge Model ◽  
Entrapped Air ◽  
Air Pockets ◽  
Uplift Forces

Recent devastations caused by tsunami and hurricanes and the inevitability of future hurricanes making landfall have focused attention on the need to assess the vulnerability of coastal structures, and bridges in particular. Findings from a series of experiments conducted on an 1:35 scale bridge model with girders under a solitary-wave flow are presented here. Side panels are added to the bridge model to trap air pockets between the girders. A range of elevations is considered, including cases where the bottom of the deck is just above the water surface and girders are submerged, to where girders are fully elevated above the water surface. Wave parameters tested include four water depths and five wave amplitudes. A qualitative comparison is made between results for forces on the trapped-air model and results from the same set of wave parameters on a model where the side panels are removed and air is allowed to escape. Results show effects of water particle velocity, buoyancy, air compression and sloshing all have effects on both horizontal forces in the direction of wave propagation and vertical uplift forces. In particular, in the case where air is trapped between girders and cannot escape, uplift forces are considerably larger when bridge elevation is such that the girders are fully elevated above the still water level or are slightly submerged.

scholarly journals Assessment of Numerical Methods for Plunging Breaking Wave Predictions

2021 ◽  
Vol 9 (3) ◽  
pp. 264
Author(s):  
Shanti Bhushan ◽  
Oumnia El Fajri ◽  
Graham Hubbard ◽  
Bradley Chambers ◽  
Christopher Kees
Keyword(s):  
Solitary Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Wave Crest ◽  
Breaking Wave ◽  
Rans Turbulence Models ◽  
Run Up ◽  
Better Than

This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.

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