scholarly journals Wind-Driven Waves on the Air-Water Interface

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 122
Author(s):  
Harvey Segur ◽  
Soroush Khadem
Keyword(s):  
Free Surface ◽  
Water Waves ◽  
Wave Train ◽  
Periodic Waves ◽  
Water Interface ◽  
Local Dynamics ◽  
Air Water Interface ◽  
The Waves ◽  
Two Fluid ◽  
Insight Into

An ocean swell refers to a train of periodic or nearly periodic waves. The wave train can propagate on the free surface of a body of water over very long distances. A great deal of the current study in the dynamics of water waves is focused on ocean swells. These swells are typically created initially in the neighborhood of an ocean storm, and then the swell propagates away from the storm in all directions. We consider a different kind of wave, called seas, which are created by and driven entirely by wind. These waves typically have no periodicity, and can rise and fall with changes in the wind. Specifically, this is a two-fluid problem, with air above a moveable interface, and water below it. We focus on the local dynamics at the air-water interface. Various properties at this locality have implications on the waves as a whole, such as pressure differentials and velocity profiles. The following analysis provides insight into the dynamics of seas, and some of the features of these intriguing waves, including a process known as white-capping.

scholarly journals Effect of the Air-Water Interface on the Conformation of Amyloid Beta

2020 ◽  
Author(s):  
Suman Samantray ◽  
David Cheung
Keyword(s):  
Conformational Change ◽  
Amyloid Beta ◽  
Md Simulation ◽  
Experimental Studies ◽  
Water Interface ◽  
Air Water Interface ◽  
Protein Conformational Change ◽  
Protein Fibrillation ◽  
Insight Into

Using MD simulation the conformation of the fibril forming protein amyloid beta at the air-water interface. It is found that adsorption at the air-water interface induces the formation of aggregation prone alpha-helical conformations, consistent with experimental studies of amyloid beta. Adsorption on the air-water interface also reduces the number of distinct conformations that the protein exhibits. This provides insight into the role of protein conformational change into the enhancement of protein fibrillation at interfaces.

scholarly journals Effect of the Air-Water Interface on the Conformation of Amyloid Beta

2020 ◽  
Author(s):  
Suman Samantray ◽  
David Cheung
Keyword(s):  
Conformational Change ◽  
Amyloid Beta ◽  
Md Simulation ◽  
Experimental Studies ◽  
Water Interface ◽  
Air Water Interface ◽  
Protein Conformational Change ◽  
Protein Fibrillation ◽  
Insight Into

Using MD simulation the conformation of the fibril forming protein amyloid beta at the air-water interface. It is found that adsorption at the air-water interface induces the formation of aggregation prone alpha-helical conformations, consistent with experimental studies of amyloid beta. Adsorption on the air-water interface also reduces the number of distinct conformations that the protein exhibits. This provides insight into the role of protein conformational change into the enhancement of protein fibrillation at interfaces.

The transmission of surface waves under surface obstacles

1961 ◽  
Vol 57 (3) ◽  
pp. 638-668 ◽  
Author(s):  
F. Ursell
Keyword(s):  
Free Surface ◽  
Surface Waves ◽  
Transmission Coefficient ◽  
Cross Section ◽  
Water Waves ◽  
Wave Train ◽  
Circular Cross Section ◽  
Great Distance ◽  
The Body ◽  
Radius Of Curvature

ABSTRACTA train of surface waves (water waves under gravity) is normally incident on a cylinder with horizontal generators fixed near the free surface, and is partially transmitted and partially reflected. At a great distance behind the cylinder the wave motion tends to a regular wave train travelling towards infinity; the ratio of its amplitude to the amplitude of the incident wave is the transmission coefficient . The transmission coefficient is studied when the wavelength is short compared to the dimensions of the body; physically (though not for engineering applications) this is the most interesting range of wavelengths, which corresponds to the range of shadow formation and ray propagation in optics and acoustics. The waves are then confined to a thin layer near the free surface, and the transmission under a partially immersed obstacle is then small. In the calculation the boundary condition at the free surface is linearized, viscosity is neglected, and the motion is assumed to be irrotational.At present the transmission coefficient is known only for a few configurations, all of them relating to infinitely thin plane barriers. A method is now given which is applicable to cylinders of finite cross-section and which is worked out in detail for a half-immersed cylinder of circular cross-section. The solution of the problem is made to depend on the solution of an integral equation which is solved by iteration. Only the first two terms can be obtained with any accuracy, and it appears at first that this is not sufficient to give the leading term in the transmission coefficient at short wavelengths; this difficulty is characteristic of transmission problems. By various mathematical devices which throw light on the mechanism of wave transmission, it is, nevertheless, found possible to prove that the transmission coefficient for waves of short wavelength λ and period 2π/ω incident on a half-immersed circular cylinder of radius a is asymptotically given bywhen N = 2πα/λ = ω2α/g is large. Earlier evidence had pointed towards an exponential law. It is suggested that transmission coefficients of order N−4 are typical for obstacles having vertical tangents and finite non-zero radius of curvature at the points where they meet the horizontal mean free surface. For obstacles having both front and rear face plane vertical to a depth a, is probably of order e−2N approximately; if only one of the two faces is plane vertical, is probably of order e−N approximately. Thus is seen to depend critically on the details of the cross-section.

Nonlinear effects upon waves near caustics

1979 ◽  
Vol 292 (1392) ◽  
pp. 341-370 ◽  
Keyword(s):  
Water Waves ◽  
Wave Train ◽  
Nonlinear Effects ◽  
Companion Paper ◽  
Exceptional Case ◽  
Wave Intensity ◽  
One Dimensional ◽  
Uniform Medium ◽  
The Waves ◽  
Interpretative Framework

According to linear theory the wave intensity of a slowly varying wave train becomes particularly large near caustics. In this paper it is shown how the waves are modified when the wave intensity is sufficient for nonlinear effects to begin to be important. Two types of near-linear caustics can arise in which nonlinearity either tends to advance or to retard the reflexion of waves from the caustic. General examples are given in terms of one-dimensional wave propagation, and of propagation in a uniform medium. Detailed consideration is given to a particular example: small-amplitude water waves on deep currents. This helps to provide an interpretative framework for the large-amplitude results presented in the companion paper (Peregrine & Thomas 1979). For the more exceptional case of triple roots, or cusped caustics, the increase in wave intensity is even more dramatic. In three appendices the analysis for caustics is extended to some higher-order cases.

SUPRAMOLECULAR CHIRALITY OF THE LANGMUIR-BLODGETT FILMS OF AN ACHIRAL 2-(HEPTADECYL)PHENANTHRO[9, 10-d]IMIDAZOLE

2006 ◽  
Vol 05 (06) ◽  
pp. 689-695
Author(s):  
JING YUAN ◽  
MINGHUA LIU
Keyword(s):  
Aromatic Ring ◽  
Water Interface ◽  
Blodgett Film ◽  
Langmuir Blodgett ◽  
Supramolecular Chirality ◽  
Air Water Interface ◽  
Langmuir Blodgett Films ◽  
Langmuir Blodgett Film ◽  
Cooperative Arrangement ◽  
Insight Into

A novel amphiphilic compound, 2-(heptadecyl)phenanthro[9, 10-d]imidazole (PhImC17), was synthesized and its assembly at the air/water interface was investigated. It has been found that although the compound was achiral, it can form a chiral Langmuir–Blodgett film through the interfacial organization. The larger aromatic ring of the compound, which caused the cooperative arrangement of the chromophore in the assembled ultrathin film, was suggested to play an important role in forming such supramolecular chirality. A comparison between the supramolecular chirality of the PhImC17 film with that of previously published 2-heptadecyl-naphtha[2, 3]imidazole film was performed and a further insight into the supramolecular chirality of the system from achiral molecules was proposed.

scholarly journals MODEL STUDIES OF IMPULSIVELY-GENERATED WATER WAVES

1966 ◽  
Vol 1 (10) ◽  
pp. 26 ◽  
Author(s):  
Jan M. Jordaan
Keyword(s):  
Water Waves ◽  
Wave Train ◽  
Sudden Change ◽  
Underwater Explosion ◽  
Model Studies ◽  
Wave Basin ◽  
Wave Heights ◽  
Time Of Travel ◽  
The Impact ◽  
The Waves

The wave action due to a sudden impulse in a body of water was studied in a wave basin with beach in the laboratory. Waves were impulsively generated in the 90 ft. tank of water, 3 ft. deep, by the impact or sudden withdrawal of a paraboloidal plunger 14 ft. in diameter. The waves had a dominant height of 2 inches and period of 3 seconds, respectively, at a distance of 50 ft. from the plunger. Such waves are scale representations of those generated by sudden impulses in the ocean, such as an underwater nuclear explosion, a sudden change in the ocean bed due to earthquakes, or the impact of a land slide. The waves produced by a downward impulse, or by an underwater explosion, form a dispersive system: whose properties are not constant as in a uniform progressive wave train. Wave periodicities, celerities and wave lengths increase with time of travel and wave heights decrease with travel distance. Theory has already been developed to predict the wave properties at a given travel time and distance for given source energy, displacement and travel path depth profile (Jordaan 1965). Measurements agree fairly well with predictions.

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