Numerical Study of Non-Linear Wave Run-Up Around a Circular Cylinder in Regular Waves

2021 ◽  
Vol 114 (sp1) ◽  
Author(s):  
Jong-Hyun Lee ◽  
Bonguk Koo
Keyword(s):  
Circular Cylinder ◽  
Numerical Study ◽  
Linear Wave ◽  
Regular Waves ◽  
Non Linear ◽  
Run Up

scholarly journals A numerical study of glacier advance over deforming till

2010 ◽  
Vol 4 (3) ◽  
pp. 359-372 ◽  
Author(s):  
G. J.-M. C. Leysinger Vieli ◽  
G. H. Gudmundsson
Keyword(s):  
Effective Viscosity ◽  
Numerical Study ◽  
Thickness Distribution ◽  
Plug Flow ◽  
Linear Wave ◽  
Sediment Layer ◽  
Mixed Flow ◽  
Model Experiments ◽  
Non Linear ◽  
Glacier Advance

Abstract. The advance of a glacier over a deforming sediment layer is analysed numerically. We treat this problem as a contact problem involving two slowly-deforming viscous bodies. The surface evolution of the two bodies, and of the contact interface between them, is followed through time. Using various different non-linear till rheologies, we show how the mode of advance depends on the relative effective viscosities of ice and till. Three modes of advances are observed: (1) overriding, where the glacier advances through ice deformation only and without deforming the sediment; (2) plug-flow, where the sediment is strongly deformed, the ice moves forward as a block and a bulge is built in front of the glacier; and (3) mixed-flow, where the glacier advances through both ice and sediment deformation. For the cases of both overriding and mixed-flow, an inverse depth-age relationship within the ice is obtained. A series of model experiments show the contrast in effective viscosity between ice and till to be the single most important model parameter defining the mode of advance and the resulting thickness distribution of the till. Our model experiments indicate that the thickness of the deforming till layer is greatest close to the glacier front. Measurements of till thickness taken in such locations may not be representative of deforming till thickness elsewhere. Given sufficiently large contrast in effective viscosity between ice and till, a sediment bulge is formed in front of the glacier. During glacier advance, the bulge quickly reaches a steady state form strongly resembling single-crested push moraines. Inspection of particle paths within the sediment bulge, shows that particles within the till travel at a different speed from the bulge itself, and the push moraine to advance as a form-conserving non-linear wave.

Non-Linear Wave Runup Along the Side of Ships Causing Green Water Problems: Experiments and First CFD Calculations

2014 ◽  
Author(s):  
Bas Buchner ◽  
Joris van den Berg ◽  
Joop Helder ◽  
Tim Bunnik
Keyword(s):  
Irregular Waves ◽  
Green Water ◽  
Linear Wave ◽  
Wave Direction ◽  
Wave Runup ◽  
Complex Processes ◽  
Non Linear ◽  
Run Up ◽  
Spilling Breakers ◽  
Water Problems

Large relative wave motions along the side of a ship can lead to green water on the deck. With a simplified test setup of a thin plate under an angle with the wave direction (to separate non-linear wave run up from motion effects), the non-linear wave reflection along the side of ships is studied in the present paper. These pilot tests with regular and irregular waves gave new insight in the process of non-linear wave run up with plunging and spilling breakers close to the plate. The complex processes observed made clear that linear or second order models will not be able to predict this behavior accurately. Previously [1] it was concluded that CFD methods that allow wave breaking are necessary for a prediction of these important effects. In the present paper a first pilot study is presented with an improved Volume of Fluid (VoF) Method. It is concluded that the method is in principle able to present these relative wave motions, but that a finer gridding is necessary to study the detailed flows.

Non-Linear Wave Diffraction Around a Moored Ship

2004 ◽  
Author(s):  
J. Zang ◽  
R. Gibson ◽  
P. H. Taylor ◽  
R. Eatock Taylor ◽  
C. Swan
Keyword(s):  
Wave Diffraction ◽  
Scattering Problem ◽  
Wave Interaction ◽  
Wave Structure ◽  
Second Order ◽  
Linear Wave ◽  
Wave Impact ◽  
Non Linear ◽  
Focused Wave ◽  
Run Up

The objective of this research, part of the FP5 REBASDO Programme, is to examine the effects of directional wave spreading on the nonlinear hydrodynamic loads and the wave run-up around the bow of a floating vessel (FPSO) in random seas. In this work, the non-linear wave scattering problem is solved by employing a quadratic boundary element method. An existing scheme (DIFFRACT developed in Oxford) has been extended to deal with uni-directional and directional bi-chromatic input wave systems, calculating second-order wave diffraction under regular waves and focused wave groups. The second order wave interaction with a floating vessel in a unidirectional focused wave group is presented in this paper. Comparison of numerical results and the experimental measurements conducted at Imperial College shows excellent agreement. The second-order free surface components at the bow of the ship are very significant, and cannot be neglected if one requires accurate prediction of the wave-structure interaction; otherwise a major underestimation of the wave impact on the structure could occur.

Non-Linear Wave Run-Up Along the Side of Sailing Ships Causing Green Water on Deck: Experiments and Deterministic Calculations

2020 ◽  
Author(s):  
Sanne van Essen ◽  
Henry Bandringa ◽  
Joop Helder ◽  
Bas Buchner
Keyword(s):  
Green Water ◽  
Linear Wave ◽  
Extreme Wave ◽  
Drift Speed ◽  
Highly Nonlinear ◽  
Small Wave ◽  
Non Linear ◽  
Run Up ◽  
Sailing Ship ◽  
Different Levels

Abstract Experiments with a flat plate in oblique waves at different speeds, wave conditions, headings and drift speed were done to evaluate non-linear wave run-up along a sailing ship. Both the incoming and diffracted part of the run-up were highly nonlinear in all test conditions. The run-up was larger at 135 than at 150 deg heading, the influence of speed was small, wave steepness increased run-up up to the point of breaking and a drift speed decreased the run-up. Most of the observed differences were larger than the seed and basin variability. (Semi-) linear diffraction methods are not sufficient to predict the highest runup crests, but applying them to screen for critical events could be further studied. CFD is able to accurately predict the nonlinear run-up in such selected events. Combining different levels of tools seems the most efficient way to predict extreme wave events such as green water due to run-up.

scholarly journals Numerical Investigation of Wave-Body Interactions in Shallow Water

2014 ◽  
Author(s):  
Yi Luo ◽  
Torgeir Vada ◽  
Marilena Greco
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Numerical Study ◽  
Surface Boundary ◽  
Regular Waves ◽  
Incoming Wave ◽  
Surface Boundary Conditions ◽  
First Case ◽  
Non Linear ◽  
Linear Effects

Present investigation is based on a numerical study using a time-domain Rankine panel method. The effort and novelty is to extend the applicability of the solver to shallower waters and to steeper waves by including additional non-linear effects, but in a way so to limit the increase in computational costs. The challenge is to assess the improvement with respect to the basic formulation and the recovery of linear theory in the limit of small waves. The wave theories included in the program are Airy, Stokes 5th order and Stream function. By their comparison the effect of the incoming-wave non-linearities can be investigated. For the free-surface boundary conditions two alternative formulations are investigated, one by Hui Sun [1] and one developed here. The two formulations combined with the above-mentioned wave theories are applied to two relevant problems. The first case is a fixed vertical cylinder in regular waves, where numerical results are compared with the model tests by Grue & Huseby [2]. The second case is a freely floating model of a LNG carrier (with zero forward speed) in regular waves, where computations are compared with the experimental results from the EC project “Extreme Seas”. This comparison revealed several challenges such as how to interpret/post process the experimental data. Some of these are described in the paper. After careful handling of both computed and measured data the comparisons show reasonable agreement. It is proven that including more non-linear effects in the free-surface boundary conditions can significantly improve the results. The formulation by Hui Sun gives better results compared to the linear condition, but the present formulation is shown to provide a further improvement, which can be explained through the nonlinear terms included/retained in the two approaches.

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