scholarly journals Wave Trajectory Study on the Coast of Lhoknga, Aceh Besar, Indonesia: A Numerical Model Approach

2018 ◽  
Vol 20 (1) ◽  
pp. 30 ◽  
Author(s):  
Ichsan Setiawan ◽  
Mohammad Irham
Keyword(s):  
Numerical Model ◽  
Wave Height ◽  
Coastal Waters ◽  
Wave Breaking ◽  
Numerical Study ◽  
High Tide ◽  
Two Dimensional ◽  
Maximum Wave Height ◽  
Wave Refraction ◽  
Model Approach

A numerical model of wave trajectory using shoaling and refraction formula was proposed in the coastal waters of Lhoknga, Aceh Besar, Indonesia. The developed model used a two dimensional (2D) numerical methods for wave trajectory with the input of wave height and period; 0.62 m and 8 second for high tide and 0.47 m and 6 second for low tide. This model was tested on site during low tide and high tide conditions for verification. The purpose of this numerical study is to trace the distribution of wave trajectory because of shoaling, wave breaking, and wave refraction. The model determines the wave height and crest pattern of the ray wave trajectory. The simulation result shows the pattern of the wave propagation at Lhoknga beach moves from the northwest to the east and south of the coast. The model also informs that the maximum wave height during high tide condition is 1.72 m and 1.31 m during low tide condition. The result indicates that the coast of Lhoknga has moderate wave conditions caused by a gentle beach bathymetry slope.

RANS Simulation on Wave Blocking and Breaking of Water Surface Waves Propagating on Current

2014 ◽  
Author(s):  
Bo Peng ◽  
Ning Ma ◽  
Xiechong Gu
Keyword(s):  
Numerical Model ◽  
Wave Height ◽  
Wave Breaking ◽  
Large Scale ◽  
Water Channel ◽  
Rogue Waves ◽  
Offshore Structures ◽  
Navier Stokes ◽  
Circulating Water ◽  
Wave Blocking

Wave-current interaction, a common phenomenon in the areas of estuary and gulf, is also notable in deep water sea area. When the current is strong enough, wave “blocking” accompanied by wave breaking takes place and leads to hazard sea conditions. On the other hand, wave countering current is also thought to be one of the main causes of occurrence of rogue waves in the ocean, which imperils offshore structures and is of much importance for research. Knowing this, viscous flow of wave generation on current is simulated by using Reynolds-Averaged-Navier-Stokes (RANS) equation for better understanding of its mechanism and flow field. In this study, two-dimensional waves propagating without current, along and against pre-existing large-scale current have been investigated. The validation of calculation has been demonstrated through comparing with preliminary experiments in Circulating Water Channel (CWC). When propagating in counter-current, wave is steepened and wave height increases dramatically, thus wave breaking occurs occasionally. Therefore, the variation of wave height and steepness with current velocity has been analyzed quantitatively. It has been confirmed that wave “blocking” occurs when current speed is comparable with group velocity of waves. And this is analyzed in detail in terms of kinematics, energy transfer and others. Accordingly, wave breaking is evaluated by the well-known classical wave breaking criterion. Furthermore, the proposed viscous model is compared with “simple bore dissipation model” to evaluate energy dissipation of wave breaking and improvement of numerical model for wave blocking is introduced. It has been shown that the present numerical model is applicable to reproduce the wave blocking and breaking phenomenon and it will be useful for future engineering purpose on predicting real sea conditions.

A parametric study of breaking bow waves using a 2D + T Technique

2011 ◽  
Vol 687 ◽  
pp. 540-570 ◽  
Author(s):  
Eric Maxeiner ◽  
Mostafa Shakeri ◽  
James H. Duncan
Keyword(s):  
Wave Height ◽  
Contact Point ◽  
Vertical Plane ◽  
Phase Speed ◽  
Wave Crest ◽  
Two Dimensional ◽  
Maximum Wave Height ◽  
Ship Model ◽  
Wave Maker ◽  
Maximum Contact

AbstractA mechanical two-dimensional wave maker with a flexible surface was used to create waves similar to those formed at the bow of a moving ship. Utilizing the two-dimensional plus time (2D + T) approximation, the wave maker was programmed so that its deformable wave board created a time sequence of shapes that simulated the line of intersection between one side of the hull of a slender ship model moving at constant speed and an imaginary vertical plane oriented normal to the ship model track. However, instead of simulating a particular ship hull, the wave maker was set to produce a parametric set of flat plate motions that represent components of typical bow shapes. The resulting surface waves were measured using a cinematic laser-induced fluorescence technique and the resulting wave profiles were analysed. A large variation of wave crest shapes was observed. An assortment of wave characteristics including the maximum contact point height, maximum wave height and plunging jet geometry were measured and related to the corresponding wave maker motion parameters. Despite the variety of wave maker motions and resulting wave crest shapes, it was observed that the gross parameters describing the wave, such as the maximum wave height, maximum contact point height and wave phase speed, correlate strongly with the wave maker velocity along the water line. Details of the crest shape at the moment of incipient breaking showed a stronger dependence on the initial acceleration of the wave board.

Numerical study on flow characteristics of rotor pumps including cavitation

2014 ◽  
Vol 229 (14) ◽  
pp. 2626-2638 ◽  
Author(s):  
Yingyuan Liu ◽  
Leqin Wang ◽  
Zuchao Zhu
Keyword(s):  
Numerical Model ◽  
Mass Flow ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Two Dimensional ◽  
Flow Rates ◽  
Factors Affecting ◽  
Remarkable Effect ◽  
Mass Flow Rates

This work is purposed to study the flow characteristics of rotor pumps including cavitation. First, a simplified two-dimensional numerical model is developed and computing strategies of the numerical analysis for cavitation are set up, including the selection of cavitation model and its parameters. Second, the reliability and accuracy of the two-dimensional numerical model are verified by experimental results. Then, several factors affecting the cavitation are discussed, including the rotational speeds, pressure differences, clearance sizes, and inlet pressures. For different rotational speeds and pressure differences, the mass flow rates with cavitation are a little larger than that without cavitation, but the amplitudes of the mass flow rates with cavitation are much larger than that without cavitation. Meanwhile, the volume fraction of the water vapor increases with the increasing speeds and the decreasing pressure differences. However, compared with the influence of rotational speeds, the influence of the pressure differences on the vapor contents is relatively smaller. Regarding the clearance size, the smaller the clearance size is, the stronger the cavitation will be. Furthermore, the clearance size between two rotors has a larger effect on the cavitation than that between rotor and pump case. For inlet pressure, it has a little effect on the mass flow rates when cavitation is not considered, but it presents a remarkable effect for the model with cavitation. In addition, the peaks of the volume fractions of vapor and the mass flow rates generally offset backward with the decreasing inlet pressures.

scholarly journals A numerical model for simulation of near-shore waves and wave induced currents using the depth-averaged non-hydrostatic shallow water equations with an improvement of wave energy dissipation

2020 ◽  
Vol 20 (2) ◽  
pp. 155-172
Author(s):  
Phung Dang Hieu ◽  
Phan Ngoc Vinh
Keyword(s):  
Numerical Model ◽  
Shallow Water ◽  
Wave Height ◽  
Shallow Water Equations ◽  
Wave Breaking ◽  
Water Model ◽  
Height Distribution ◽  
Time Duration ◽  
Wave Energy Dissipation ◽  
Near Shore

This study proposes a numerical model based on the depth-integrated non-hydrostatic shallow water equations with an improvement of wave breaking dissipation. Firstly, studies of parameter sensitivity were carried out using the proposed numerical model for simulation of wave breaking to understand the effects of the parameters of the breaking model on wave height distribution. The simulated results of wave height near the breaking point were very sensitive to the time duration parameter of wave breaking. The best value of the onset breaking parameter is around 0.3 for the non-hydrostatic shallow water model in the simulation of wave breaking. The numerical results agreed well with the published experimental data, which confirmed the applicability of the present model to the simulation of waves in near-shore areas.

scholarly journals Two-Dimensional Numerical Study of the Microclimate Generated in Three Screenhouses for the Climatic Conditions of the Colombian Caribbean

2021 ◽  
Vol 39 (2) ◽  
pp. 460-468
Author(s):  
Edwin Villagran
Keyword(s):  
Wind Speed ◽  
Numerical Model ◽  
Production Systems ◽  
Numerical Study ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Warm Climate ◽  
Wind Speeds ◽  
Average Temperature ◽  
Roof Area

Insect proof screenhouse is increasingly used in tropical countries with a warm climate, as this type of structure is more economical than greenhouses and gives farmers the opportunity to optimize their production systems. In this work we used an experimentally validated two-dimensional numerical model, the objective was to study the air flow patterns and the thermal and hygrometric behavior of three screenhouses differentiated in their geometric configuration of the roof area and under four (4) outside wind speeds. The results obtained allowed us to find that the airflow speed inside the screenhouse can be maximized with respect to the most critical scenario by 29% for a wind speed of 0.5 ms-1 and up to 292% for a wind speed of 3.0 ms-1, which generates reductions in the average temperature inside the structure of -0.2℃ (0.5 ms-1) and up to -2.2℃ (3 ms-1). While the relative humidity presented values of 1.6% and 6.3% higher for these same speeds.

Numerical Study on Two-dimensional Magnetic Photonic Crystals Made of Magnetized Ferrites

PIERS Online ◽  
2007 ◽  
Vol 3 (3) ◽  
pp. 305-307 ◽  
Author(s):  
Jie Xu ◽  
Ping Chen ◽  
Yue Shi ◽  
Xin-Yi Ji ◽  
Ai-Min Jiang ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Numerical Study ◽  
Two Dimensional ◽  
Magnetic Photonic Crystals

Co-planar two-dimensional Metal-Insulator-Semiconductor Capacitor: Numerical study of the device electrostatics.

2017 ◽  
Author(s):  
Varun Bheemireddy
Keyword(s):  
Space Charge ◽  
High Performance ◽  
Numerical Study ◽  
2D Materials ◽  
Space Charge Density ◽  
Two Dimensional ◽  
Short Channel ◽  
Metal Insulator ◽  
Metal Insulator Semiconductor ◽  
New Family

The two-dimensional(2D) materials are highly promising candidates to realise elegant and e cient transistor. In the present letter, we conjecture a novel co-planar metal-insulator-semiconductor(MIS) device(capacitor) completely based on lateral 2D materials architecture and perform numerical study of the capacitor with a particular emphasis on its di erences with the conventional 3D MIS electrostatics. The space-charge density features a long charge-tail extending into the bulk of the semiconductor as opposed to the rapid decay in 3D capacitor. Equivalently, total space-charge and semiconductor capacitance densities are atleast an order of magnitude more in 2D semiconductor. In contrast to the bulk capacitor, expansion of maximum depletion width in 2D semiconductor is observed with increasing doping concentration due to lower electrostatic screening. The heuristic approach of performance analysis(2D vs 3D) for digital-logic transistor suggest higher ON-OFF current ratio in the long-channel limit even without third dimension and considerable room to maximise the performance of short-channel transistor. The present results could potentially trigger the exploration of new family of co-planar at transistors that could play a signi significant role in the future low-power and/or high performance electronics.<br>

Investigation of two-dimensional nonstationary processes of outflow a gas-saturated liquid from axisymmetric vessels

2012 ◽  
Vol 9 (1) ◽  
pp. 47-52
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Buzina
Keyword(s):  
Comparative Analysis ◽  
Numerical Model ◽  
Liquid Mixture ◽  
Phase Model ◽  
Test Problems ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Saturated Liquid ◽  
Two Phase ◽  
One Dimensional

The two-dimensional and two-phase model of the gas-liquid mixture is constructed. The validity of numerical model realization is justified by using a comparative analysis of test problems solution with one-dimensional calculations. The regularities of gas-saturated liquid outflow from axisymmetric vessels for different geometries are established.

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