• Journal of the Chungcheong Mathematical Society
• /
• v.35 no.2
• /
• pp.137-147
• /
• 2022

In this paper, we considered the Dirichlet initial boundary value problem of a nonlinear viscoelastic wave equation with nonlinear damping and source terms, and investigated finite time blow-up phenomena of the solutions to the equation with arbitrary positive initial data, under suitable conditions.

• Earthquakes and Structures
• /
• v.13 no.5
• /
• pp.465-471
• /
• 2017

This work derives a generalized time fractional differential equation governing wave propagation in a radially vibrating non-classical cylindrical medium. The cylinder is made of a transversely isotropic hyperelastic John's material which obeys frequency-dependent power law attenuation. Employing the definition of the conformable fractional derivative, the solution of the obtained generalized time fractional wave equation is expressed in terms of product of Bessel functions in spatial and temporal variables; and the resulting wave is characterized by the presence of peakons, the appearance of which fade in density as the order of fractional derivative approaches 2. It is obtained that the transversely isotropic structure of the material of the cylinder increases the wave speed and introduces an additional term in the wave equation. Further, it is observed that the law relating the non-zero components of the Cauchy stress tensor in the cylinder under consideration generalizes the hypothesis of plane strain in classical elasticity theory. This study reinforces the view that fractional derivative is suitable for modeling anomalous wave propagation in media.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.10a
• /
• pp.138-143
• /
• 2001

Based on mild slope equation and parabolic approximation the forward diffraction of monochromatic waves by a straight breakwater are studied numerically. The characteristics and effects of stem wave along breakwater and the relations between the stem wave and incident wave angle are discussed.

• Journal of Ocean Engineering and Technology
• /
• v.34 no.6
• /
• pp.419-427
• /
• 2020

In this study, a particle image velocimetry (PIV)-based pressure estimation method was investigated, with application to the wave-in-deck loading phenomenon. An experimental study was performed in a two-dimensional wave tank using a fixed deck structure under a focused wave, obtaining local pressures by pressure sensors, global loads by load cells, and instantaneous velocity fields using the PIV measurement technique. The PIV-based pressure estimation method was applied using the Euler equation as the governing equation, and the proper time step for the wave impact pressure was studied using the normalized root-mean-square deviation. The pressure estimation method showed good agreement for the local impact pressure in comparison with the measured pressure by the pressure sensors. However, some differences were observed in the peak pressure due to the limitations of the Euler equation and the sampling rate of the measurement system. Using the estimation method, the pressure fields during wave-in-deck loading were determined in the study, with an analysis of the mechanism of impact and negative pressure occurrence.

• Journal of Korean Port Research
• /
• v.13 no.1
• /
• pp.155-166
• /
• 1999

The construction of the coastal structures and reclamation work causes the circulation reduced in the semi-closed inner water area and the unbalanced sediment budget of beach results in an alteration of beach topography. Among the various fluid motions in the nearshore zone water particle motion due to wave and wave-induced currents are the most responsible for sediment movement. Therefore it is needed to predict the effect of the environmental change because of development and so the prediction of wave transformation dose. The purpose of this study is to introduce the relation between waves wave-induced currents and sediment movement. In this study we will show numerical method using energy conservation equation involving reflection diffraction and reflection and the surfzone energy dissipation term due to wave breaking is included in the basic equation. For the wave-induced current the momentum equation was combined with radiation stresses lateral mixing and friction Various information is required in the prediction of wave-induced current depending on the prediction tool. We can predict changes in wave-induced current from the distribution of wave especially near the wave breaking zone. To evaluate these quantities we have to know the local condition of waves mean sea level and so on. The results from the wave field and wave-induced current field deformation models are used as input data of the sediment transport and bottom change model. Numerical model were established by a finite difference method then were applied to the development plan of the eastern Pusan coastal zone Yeonhwa-ri and Daebyun fishing port. We represented the result with 2-D graphics and made comparison between before and after development.

• Coupled systems mechanics
• /
• v.1 no.2
• /
• pp.183-204
• /
• 2012

A method for the analysis of wave scattering in 3-D elastic full space is developed by means of the coupled boundary-volume integral equation, which takes into account the effects of both the boundary of inclusions and the uctuation of the wave field. The wavenumber domain formulation is used to construct the Krylov subspace by means of FFT. In order to achieve the wavenumber domain formulation, the boundary-volume integral equation is transformed into the volume integral equation. The formulation is also focused on this transform and its numerical implementation. Several numerical results clarify the accuracy and effectiveness of the present method for scattering analysis.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.16 no.2
• /
• pp.103-107
• /
• 2004

Empirical equation has been developed by employing the new non-dimensional physical number 'wave action slope' for the estimation of breakwater armor weight. Van der Meer(1987) introduced Iribarren number for the same purpose, but his equation shows very different trend of distribution with the condition of Iribarren number. On the other hand the equation related with wave action slope keeps the same trend of distribution over the whole region. When the parameter is related to the Iribarren number, the equation of wave action slope has a very high accuracy.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.11 no.1
• /
• pp.68-74
• /
• 1999

The Green function method is widely used for the analysis of waves in a harbor with a constant depth. In extending this method to a wave field over arbitrary depth, a generalized and convenient method is needed to obtain unit solutions for waves emerging from a point source. For this purpose, a parabolic wave equation is derived to approximate the mild-slope equation written in terms of polar coordinates. Usefulness of the equation obtained is examined through trial computations.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.733-742
• /
• 2020

Taking the cylindrical float of the floating fence of a floating litter collection device as the research object, based on the shallow immersion characteristics of the cylindrical float, the Morison equation is modified, and the interaction between regular waves and the partially immersed horizontal cylindrical float is discussed in combination with scale model test. The results show that the modified Morison equation can accurately predict the wave force of the horizontal cylindrical float and reveal the influence of amplitude, immersion depth and period on the wave force of the cylindrical float. For partially immersed cylindrical floats, the wave force increases with the increase in wave height and decays with the increase in period. The positive value distribution of the wave force is larger than that of the negative direction, and the difference between the positive and negative directions is mainly affected by the immersion depth.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.7
• /
• pp.18-25
• /
• 2005

In this study, the main focus is the simulation of acoustic wave scattering in trailing edge and the analysis of the generation mechanism of instability wave by the interaction of trailing edge, shear flow and initial disturbance. The numerical algorithm is based on CFD/CAA hybrid method with high-order computational aeroacoustic method. It is found that steady mean flow gradient terms play a crucial role on the generation of instability wave through the comparison of simulations of Simple Linearized Euler Equation and Full Linearized Euler Equation. Through the comparison with the results of Full Navier-Stokes Equation, it is reasonable and efficient to use the Full Linearized Euler Equation in the initial generation mechanism of the instability wave near the trailing edge.