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1

A side-hinged paddle wavemaker

Sulisz W., Zdolska A.

Archives of Mechanics

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2023

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Vol. 75, nr 1-2

213--242

EN

Theoretical investigations were conducted to study the generation of transient nonlinear water waves by a novel side-hinged paddle wavemaker. A 3D nonlinear solution was derived in a semi-analytical form by applying eigenfunction expansions and FFT. The solution was applied to study the features of nonlinear waves generated by a side-hinged paddle wavemaker. The results show that nonlinear terms in the free-surface boundary conditions and in the kinematic wavemaker boundary condition imply the modification of wave profiles so that wave troughs are flattered and crests are getting steeper and interaction effects between waves in a wave train increase. Moreover, these terms imply the modification of a wave spectrum. A train of originally very narrow-banded waves changes its one-peak spectrum to a multi-peak one. Theoretical results are in a fairly good agreement with experimental data. A reasonable agreement is observed between predicted and measured time series of free-surface elevations and the amplitudes of the corresponding Fourier series. The investigations show that a side-hinged paddle wavemaker is an attractive wave generation system. Simple and reliable boundary condition at the paddle enables verification of advanced 3D nonlinear models and accurate physical modeling of many phenomena where high accuracy of incoming wave properties are important.

2

Signal generation and verification process for the physical modeling of ocean waves

Gatz M., Sudański R.

Zeszyty Naukowe Akademii Marynarki Wojennej

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2017

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R. 58 nr 3 (210)

43--53

EN

This paper presents the implementation process of the design methodology for ocean waves in a laboratory tank using a wave generator, which is the basis for conducting hydrodynamic model scale research involving real sea conditions. The main focus is placed on generation of time sequences used as the control input for the wave generator and experimental verification methods for the generated waves and concluding with the results and validation of the developed process by achieving wave parameters sufficiently aligned with the theoretical model.

PL

W artykule przedstawiono proces implementacji metodologii projektowania fal oceanicznych w basenie modelowym przy wykorzystaniu generatora fal, który stanowi podstawę do hydrodynamicznych badań modelowych uwzględniających rzeczywiste warunki oceaniczne. Główny nacisk położono na generowanie przebiegów czasowych i ich wykorzystanie jako wejściowych sygnałów sterujących dla generatora fal oraz metody eksperymentalnej weryfikacji wygenerowanych w ten sposób fal. Przedstawiono także wyniki końcowe i walidację opracowanego procesu, uzyskując parametry fali odpowiednio dopasowane do modelu teoretycznego.

3

On some corrugation related dynamical problems of wheel/rail interaction

Bogacz R., Frischmuth K.

Archives of Transport

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2010

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Vol. 22, iss. 1

27-41

EN

We simulate the motion of a corrugated disk over a corrugated track under unilateral elastic contact forces. In particular, the trajectory of the geometrical contact point and the magnitude of normal forces are studied. Effects like generation of waves and cumulation of plastic deformation are considered.

PL

Przedmiotem pracy jest analiza dynamiki koła toczącego się po szynie w przypadku skorugowanych powierzchni koła i szyny. Zadanie rozwiązuje się metodą symulacji komputerowej uwzględniając działanie jednostronnych sprężystych sił kontaktowych. Szczególny nacisk położony jest na ocenę trajektorii geometrycznego punktu kontaktu oraz na wartości kontaktowych sił normalnych. Badane zjawisko generuje efekty mające wpływ na emisje fal oraz na powstanie trwałych deformacji.

4

Generation of waves in two superposed fluids covered by an elastic plate in the presence of running stream

Dolai P.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 1

139-156

EN

This paper is concerned with the problem of two-dimensional wave generation due to an initial disturbance created at the upper surface of two superposed fluid layers in the presence of uniform running streams. The upper fluid of finite height is covered by a thin elastic plate. The lower fluid of finite depth is separated from the upper one by a common interface. Assuming linear theory, the problem is formulated as a coupled initial value problem of the velocity potentials describing the motion in the two fluids. In the mathematical analysis, the Laplace and Fourier transform techniques have been utilized to obtain the elevations at the upper fluid surface and the interface in the form of infinite integrals involving the initial elevation due to plate deflection. As a special case when the initial elevation concentrated at a point on the upper surface, these integrals are evaluated asymptotically by the method of stationary phase. The asymptotic forms of the upper surface elevation and the interface elevation are depicted graphically in a number of figures. The effects of the upper fluid covered by an elastic plate and the presence of running streams on the wave motion are discussed.

5

Interface wave generation in two fluid medium in the presence of running stream

Dolai P.

International Journal of Applied Mechanics and Engineering

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2008

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Vol. 13, no 3

669-679

EN

In this paper, a problem of two-dimensional wave generation due to initial disturbance at the interface between two superposed fluids wherein the upper fluid of finite height above the interface with a horizontal rigid lid and the lower fluid of finite depth in the presence of a uniform running stream in both the fluids is investigated. Assuming linear theory, the problem is formulated as a coupled initial value problem of the velocity potentials describing the motion in the two fluids. In the mathematical analysis, the Laplace and Fourier transform techniques have been utilized to obtain the interface depression when the initial disturbance at the interface is in the form of a prescribed interface depression or an impulse concentrated at the origin. In both the cases, the interface depression is obtained in terms of an infinite integral which is evaluated asymptotically for large time and distance by the method of stationary phase. The asymptotic forms of the interface depression are depicted graphically in a number of figures. The effect of the upper fluid and the presence of the running stream in both the fluids on the wave motion are discussed.

6

Waves generated by bottom disturbance in an ice-covered ocean

Maiti P., Mandal B. N.

International Journal of Applied Mechanics and Engineering

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2007

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Vol. 12, no 2

477-486

EN

The problem is concerned with a two-dimensional unsteady motion in an ice-covered ocean due to the transient bottom disturbance, the ice-cover being formed by a thin sheet of ice modelled as an elastic plate. Assuming linear theory, the problem is solved as an initial value problem in the velocity potential describing the motion in the fluid. Using the Laplace and Fourier transforms in time and space respectively, the depression of the ice-cover below its mean horizontal position, is obtained in terms of an integral. This integral is evaluated asymptotically for large time and distance by the method of stationary phase. Leading waves due to a transient disturbance are also obtained. The asymptotic form of the depression of the ice-cover is depicted graphically in a number of figures for different forms of the bottom disturbance and compared with the case when the upper surface is free, so as to visualize the effect of the presence of ice.

7

Generation of waves in running stream

Basu U., Ghosh P.

International Journal of Applied Mechanics and Engineering

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2003

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Vol. 8, no 1

17-26

EN

In this paper, a problem of the two-dimensional wave generation due to an initial disturbance at the free surface in an ocean of finite depth in the presence of surface tension and a uniform running stream is investigated. Using linear theory, the problem is formulated as an initial value problem for the velocity potential describing the ensuing motion in the fluid. In the mathematical analysis the Laplace and Hankel transform techniques have been utilized to obtain the elevation of the free surface in the form of an infinite integral. This is then evaluated asymptotically for large time and distance by applying the method of stationary phase. The form of the free surface is depicted graphically for two types of initial disturbances. The effect of the surface tension and the presence of the running stream on the wave motion are discussed.