Experimental and numerical investigations of temporally and spatially periodic modulated wave trains

2018 ◽  
Vol 30 (3) ◽  
pp. 034101 ◽  
Author(s):  
H. Houtani ◽  
T. Waseda ◽  
K. Tanizawa
Keyword(s):  
Numerical Investigations ◽  
Spatially Periodic ◽  
Wave Trains ◽  
Modulated Wave Trains

$ M- $truncated optical soliton and their characteristics to a nonlinear equation governing the certain instabilities of modulated wave trains

2021 ◽  
Vol 6 (9) ◽  
pp. 9208-9222
Author(s):  
Abdullahi Yusuf ◽  
◽  
Tukur A. Sulaiman ◽  
Mustafa Inc ◽  
Sayed Abdel-Khalek ◽  
...  
Keyword(s):  
Nonlinear Equation ◽  
Optical Soliton ◽  
Wave Trains ◽  
Modulated Wave Trains

scholarly journals The dynamics of modulated wave trains

2009 ◽  
Vol 199 (934) ◽  
pp. 0-0 ◽  
Author(s):  
Arjen Doelman ◽  
Björn Sandstede ◽  
Arnd Scheel ◽  
Guido Schneider
Keyword(s):  
Wave Trains ◽  
Modulated Wave Trains

Analysis of the Momentum Transfer Operated by the Breaking in Modulated Wave Trains in Wind and No-Wind Conditions

2019 ◽  
Author(s):  
Alessandro Iafrati ◽  
Massimo Falchi
Keyword(s):  
Stokes Equations ◽  
Phase Speed ◽  
Water Layer ◽  
Vertical Flux ◽  
Wave System ◽  
Initial Development ◽  
Vertical Transfer ◽  
Wave Trains ◽  
Horizontal Momentum ◽  
Modulated Wave Trains

Abstract An analysis of the flow and of the vertical transfer of the horizontal momentum induced by the breaking of modulated wave trains in wind and no-wind conditions is presented. The study is based on the results of two-dimensional numerical simulation of the Navier-Stokes equations for two-phase flow. The open source Gerris flow solver has been used, which employs a Volume of Fluid technique to capture the air-water interface. The breaking is induced through the Benjamin-Feir instability mechanism. The numerical simulations cover the entire range from the initial development of the instability, the breaking phase and the post-breaking evolution. In order to investigate the role played by the wind, a uniform wind profile, twice the phase speed, is initialized in the air phase and it is left to evolve while interacting with the wave system. Results in terms of averaged horizontal velocity and vertical flux of horizontal momentum are presented. It is shown that in the wind case the backward stresses induced at the wave troughs as a consequence of the flow separation at the crest influence significantly the flow in the upper water layer, particularly in the pre-breaking phase. No substantial differences are found between the wind and no-wind solutions in terms of the vertical transfer of horizontal momentum in the lower water layer. The vertical flux of horizontal momentum in air is consistent with the velocity reduction occurring in the wind case in the early stage.

Towing Experiment of a Hydro-Structural Container Ship Model in Bow-Quartering Modulated Wave Trains

2020 ◽  
Author(s):  
Hidetaka Houtani ◽  
Yusuke Komoriyama ◽  
Sadaoki Matsui ◽  
Masayoshi Oka ◽  
Hiroshi Sawada ◽  
...  
Keyword(s):  
Vibration Mode ◽  
Wave Train ◽  
Mode Shapes ◽  
Strain Gauges ◽  
Container Ship ◽  
Ship Model ◽  
Wave Heights ◽  
Wave Trains ◽  
Heading Angle ◽  
Modulated Wave Trains

Abstract We experimentally investigated the influence of the geometries of a modulated wave train on the vertical-bending and torsional moments acting on a container ship in bow-quartering sea conditions. We conducted a towing experiment with a hydro-structural container ship model in the Actual Sea Model Basin (ASMB) (80 m deep, 40 m wide, and 4.5 m deep) at the National Maritime Research Institute. The ship model is made of urethane foam and was designed to have similar vertical bending and torsional vibration mode shapes to an actual ship. A modulated wave train was generated in the ASMB by the higher-order spectral-method wave generation (HOSM-WG) method such that the maxim crest appeared at the center of the basin. The ship model was towed in the modulated wave train with a relative heading angle of 120 degrees. A series of tests was performed by varying the encounter timing of the ship model and the maximum crest of the modulated wave train. In the experiment, fiber-Bragg-grating strain gauges successfully measured whipping vibrations of the ship model due to a slamming impact. The experimental results revealed that the rear wave height Hr and the ratio of the rear and front wave heights Hr/Hf were the dominant parameters governing the maximum sagging and torsional moments of a ship in bow-quartering modulated wave trains.

A Laser-Interferometer Method for Determining the Forces on a Freely-Flying Model in a Shock-Tunnel

1982 ◽  
Vol 33 (3) ◽  
pp. 237-257 ◽  
Author(s):  
L. Bernstein ◽  
G.T. Stott
Keyword(s):  
Laser Interferometer ◽  
Shock Tunnel ◽  
Test Time ◽  
Prototype System ◽  
Interferometric Method ◽  
Dark Light ◽  
Geometric Size ◽  
Wave Trains ◽  
Modulated Wave Trains ◽  
Interferometer Method

SummaryConventional force-balances, “accelerometer balances” and photographic monitoring of freely-flying models are not suitable for use in the Q.M.C. shock tunnel where the force levels are of order 10N for flow durations of about 1 ms. An interferometric method has therefore been developed for following the trajectory of a weakly-restrained model. The prototype system consists of two simple Michelson interferometers, a single He-Ne laser being employed to provide two measurement and two reference beams so that the motion of two points on the model can be followed. The measurement beams are returned by corner-cube retroreflectors carried on the model which ensures that for each measurement arm the reference and measurement beams recombine at the surface of a photo-detector. As the model moves, interference fringes are produced at the detectors, the cycle dark-light-dark corresponding to a model displacement along the measurement beam of ½λ, about 0.3μm. The frequency-modulated wave-trains produced are recorded using two transient recorders, the data being subsequently played back to a two-channel pen recorder giving a record 500 mm in length corresponding to the test time. The fringe number as a function of time is read manually, and the data analysed by curve fitting to a parabola which yields the accelerations of the measurement points. A knowledge of the inertial characteristics of the model then gives the forces on it. By suitably aligning the beams, lift and pitching moment for a ridge-delta of aspect-ratio 1 were obtained. Two models of the same geometric size but of different inertia were tested. All the data were obtained for model displacements less than 1 mm and pitch rotations less than 0.1°.

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