scholarly journals Numerical study of a Whitham equation exhibiting both breaking waves and continuous solutions

AIP Advances ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 045002
Author(s):  
Michael P. Mortell ◽  
Kieran F. Mulchrone
Keyword(s):  
Numerical Study ◽  
Breaking Waves ◽  
Continuous Solutions ◽  
Whitham Equation

scholarly journals Trim Influence on Kriso Container Ship (KCS): An Experimental and Numerical Study

2017 ◽  
Author(s):  
Emil Shivachev ◽  
Mahdi Khorasanchi ◽  
Alexander H. Day
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Study ◽  
Computational Cost ◽  
Breaking Waves ◽  
Computational Techniques ◽  
Container Ship ◽  
Towing Tank ◽  
Operational Life ◽  
Computational Fluid Dynamics Cfd

There has been a lot of interest in trim optimisation to reduce fuel consumption and emissions of ships. Many existing ships are designed for a single operational condition with the aim of producing low resistance at their design speed and draft with an even keel. Given that a ship will often sail outside this condition over its operational life and moreover some vessels such as LNG carriers return in ballast condition in one leg, the effect of trim on ships resistance will be significant. Ship trim optimization analysis has traditionally been done through towing tank testing. Computational techniques have become increasingly popular for design and optimization applications in all engineering disciplines. Computational Fluid Dynamics (CFD), is the fastest developing area in marine fluid dynamics as an alternative to model tests. High fidelity CFD methods are capable of modelling breaking waves which is especially crucial for trim optimisation studies where the bulbous bow partially emerges or the transom stern partially immerses. This paper presents a trim optimization study on the Kriso Container Ship (KCS) using computational fluid dynamics (CFD) in conjunction with towing tank tests. A series of resistance tests for various trim angles and speeds were conducted at 1:75 scale at design draft. CFD computations were carried out for the same conditions with the hull both fixed and free to sink and trim. Dynamic sinkage and trim add to the computational cost and thus slow the optimisation process. The results obtained from CFD simulations were in good agreement with the experiments. After validating the applicability of the computational model, the same mesh, boundary conditions and solution techniques were used to obtain resistance values for different trim conditions at different Froude numbers. Both the fixed and free trim/sinkage models could predict the trend of resistance with variation of trim angles; however the fixed model failed to measure the absolute values as accurately as the free model. It was concluded that a fixed CFD model, although computationally faster and cheaper, can find the optimum trim angle but cannot predict the amount of savings with very high accuracy. Results concerning the performance of the vessel at different speeds and trim angles were analysed and optimum trim is suggested.

scholarly journals Numerical Study on the Generation and Transport of Spume Droplets in Wind over Breaking Waves

Atmosphere ◽  
2017 ◽  
Vol 8 (12) ◽  
pp. 248 ◽  
Author(s):  
Shuai Tang ◽  
Zixuan Yang ◽  
Caixi Liu ◽  
Yu-Hong Dong ◽  
Lian Shen
Keyword(s):  
Numerical Study ◽  
Breaking Waves

A numerical study of intermittent sediment concentration under breaking waves in the surf zone

2007 ◽  
Vol 54 (5) ◽  
pp. 433-444 ◽  
Author(s):  
Takayuki Suzuki ◽  
Akio Okayasu ◽  
Tomoya Shibayama
Keyword(s):  
Surf Zone ◽  
Numerical Study ◽  
Sediment Concentration ◽  
Breaking Waves

A Novel Method for Generating Continuously Surfable Waves

2010 ◽  
Vol 44 (2) ◽  
pp. 7-12 ◽  
Author(s):  
Steven Schmied ◽  
Jonathan Binns ◽  
Martin Renilson ◽  
Giles Thomas ◽  
Gregor Macfarlane ◽  
...  
Keyword(s):  
Steady State ◽  
Wave Breaking ◽  
Numerical Study ◽  
River Estuary ◽  
Breaking Waves ◽  
Scale Model ◽  
Wave Mechanics ◽  
Pressure Source ◽  
Novel Method ◽  
Future Work

AbstractThis paper presents the background and initial investigation of a novel method for generating continuously surfable waves utilizing a moving pressure source. The idea is to produce continuous breaking waves using a pressure source that is rotated within an annular wave pool. The inner ring of the annulus has a sloping bathymetry to induce wave breaking. The underlying aim of the project is to understand the wave mechanics, to allow the creation of repeatable continuous “steady-state” waves.The immediate benefits of this scientific investigation will be realized by engineering the results into a surfing wave pool for recreational health use. The longer-term benefits will be developed through fundamental investigations of breaking waves.Preliminary experiments into creating a continuous steady-state wave were conducted in a towing tank using a series of pressure sources. The results have then been used to validate an initial numerical study. In addition, qualitative, full-scale experiments were carried out using a fishing vessel in a river estuary. This paper reports on the research conducted to date and plans for future work, including conducting experiments utilizing a 10-metre-diameter scale model.

scholarly journals A numerical study of breaking waves

2004 ◽  
Vol 16 (7) ◽  
pp. 2649-2667 ◽  
Author(s):  
Chiyoon Song ◽  
Ana I. Sirviente
Keyword(s):  
Numerical Study ◽  
Breaking Waves

Runup of long waves on composite coastal slopes: numerical simulations and experiment

2020 ◽  
Author(s):  
Ira Didenkulova ◽  
Andrey Kurkin ◽  
Artem Rodin ◽  
Ahmed Abdalazeez ◽  
Denys Dutykh
Keyword(s):  
Experimental Data ◽  
Shallow Water ◽  
Numerical Study ◽  
Breaking Waves ◽  
Shallow Water Theory ◽  
Wave Runup ◽  
Coastal Slope ◽  
Long Wave ◽  
Nonlinear Shallow Water Theory ◽  
Runup Height

<p>The goal of this study is to investigate the effect of the bottom shape on wave runup. The obtained results have been confronted with available analytical predictions and a dedicated numerical simulation campaign has been carried out by the team. We study long wave runup on composite coastal profiles. Two types of beach profiles are considered. The Coastal Slope 1 consists of two merged plane beaches with lengths 1.2 m and 5 m and beach slopes tan α = 1:10 and tan β = 1:15 respectively. The Coastal Slope 2 also consists of two sections: plane beach with length 1.2 m and a beach slope α, which is merged with a convex (non-reflecting) beach. The latter is constructed in the way, that its total height and length remain the same as for the Coastal Slope 1.</p><p>The study is conducted with numerical (in silico) and experimental approaches.</p><p>Experiments have been conducted in the hydrodynamic flume of the Nizhny Novgorod State Technical University n.a. R.E. Alekseev. Both composite beach profiles were constructed in 2019. The Coastal Slope 1 consists of three parts made of aluminum. The plain beach part of the Coastal Slope 2 is also made of aluminum, and the convex profile consists of two parts made of curved PLEXIGLAS organic glass. The water surface oscillations are measured using capacitive and resistive wave gauges with recording frequencies of up to 80 Hz and 100 Hz respectively. Wave runup is measured by a capacitive string sensor installed along the slope.</p><p>A series of experiments on the generation and runup of regular wave trains with a period of 1s, 2s, 3s and 4s were carried out. The water level was kept constant for all experiments and was equal to 0.3 meters. Up to now, 21 experiments have been carried out (10 and 11 experiments for each Coastal Slope respectively).</p><p>A comparative numerical study is carried out in the framework of the nonlinear shallow water theory and the dispersive theory in the Boussinesq approximation.</p><p>As a result, we compare the long wave dynamics on these two bottom profiles and discuss the influence of nonlinearity and dispersion on the characteristics of wave runup. It is shown numerically that, in the framework of the nonlinear shallow water theory, the runup height on the Coastal Slope 2 tends to exceed the corresponding runup height on the Coastal Slope 1, that also agrees with our previous results (Didenkulova et al. 2009; Didenkulova et al. 2018). Taking dispersion into account leads to an increase in the spread in values of the wave runup height. As a consequence, individual cases when the runup height on the Coastal Slope 1 is higher than on the Coastal Slope 2 have been observed. In experimental data, such cases occur more often, so that the advantage of one slope over another is no longer obvious. Note also that the most nonlinear breaking waves with a period of 1s have a greater runup height on Coastal Slope 2 for both models and most experimental data.</p>

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