Frontal collision of internal solitary waves of first mode

Terletska, K.,Jung, K.T.,Maderich, V.,Kim, K.O. Elsevier 2018 Wave motion Vol.77 No.-

<P><B>Abstract</B></P> <P>The dynamics and energetics of a frontal collision of internal solitary waves (ISW) of first mode in a fluid with two homogeneous layers separated by a thin interfacial layer are studied numerically within the framework of the Navier–Stokes equations for stratified fluid. It was shown that the head-on collision of internal solitary waves of small and moderate amplitude results in a small phase shift and in the generation of dispersive wave train travelling behind the transmitted solitary wave. The phase shift grows as amplitudes of the interacting waves increase. The maximum run-up amplitude during the wave collision reaches a value larger than the sum of the amplitudes of the incident solitary waves. The excess of the maximum run-up amplitude over the sum of the amplitudes of the colliding waves grows with the increasing amplitude of interacting waves of small and moderate amplitudes whereas it decreases for colliding waves of large amplitude. Unlike the waves of small and moderate amplitudes collision of ISWs of large amplitude was accompanied by shear instability and the formation of Kelvin–Helmholtz (KH) vortices in the interface layer, however, subsequently waves again become stable. The loss of energy due to the KH instability does not exceed 5%–6%. An interaction of large amplitude ISW with even small amplitude ISW can trigger instability of larger wave and development of KH billows in larger wave. When smaller wave amplitude increases the wave interaction was accompanied by KH instability of both waves.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Frontal collision of internal solitary waves is studied numerically. </LI> <LI> Collision results in a wave phase shift growing with wave amplitude. </LI> <LI> Nonlinear components of runup for waves of small and large amplitudes differs. </LI> <LI> Collision of waves of large amplitude leads to the shear instability. </LI> <LI> Collision of small and large amplitude waves triggers the shear instability. </LI> </UL> </P>

공진장치를 이용한 단주기파랑과 고립파의 제어

이광호(Lee Kwang Ho),정성호(Jeong Seong Ho),정진우(Jeong Jin Woo),김도삼(Kim Do Sam) 대한토목학회 2010 대한토목학회논문집 B Vol.30 No.1B

본 연구에서는 고파랑의 단주기파랑과 고립파를 동시에 저감시키기 위한 저감공으로 단주기파랑에 대해 기연구개발된 공진장치를 기설의 방파제 항구부에 부착하는 공법을 검토하였다. 이와 같은 저감공은 공진현상으로부터 단주기파랑의 입사에 너지를 포획하여 기설의 방파제 배후로 전달되는 파랑에너지를 저감시키는 특성을 갖는다. 수치해석에 있어서 단주기파랑에 대해서는 연직선Green함수에 기초한 특이점분포법을, 고립피에 대해서는 3차원수치파동수로를 이용하는 3차원혼상류해석법을 각각 적용하였고, 기존의 수치해석결과 및 실험결과와 비교 · 분석하여 본 수치해석법의 타당성을 검증하였다. 이로부터 공진장치가 없는 경우와 대비 · 검토하여 단주기파랑 및 고립파의 제어에 대한 공진장치의 제어능을 다각도로 검토한 결과, 그의 유효성을 충분히 확인할 수 있었다. 그리고 제어대상의 고립파에 대해 공진장치의 최적치수가 존재한다는 사실을 확인 할 수 있었다. The performance evaluation of a conventional Wave Resonator at the entrance of harbors against solitary wave has been performed using 3D numerical wave flume. A wave resonator has been designed for the attenuation of the transmitted wave energy by trapping the short periodic incident waves only. in this study, however, the controlled performance of the wave resonator by its various widths has been numerically investigated for solitary waves. Source distribution method based on the Green function and the 3D one-field Model for immiscible TWO-Phase flows (TWOPM-3D) using 3D numerical wave flume were used for the short-periodic waves and the solitary waves, respectively, and these models were verified through the comparisons with the previous experimental and numerical results by other researchers. It was confirmed that the wave resonator is effective enough to control the solitary waves as well as the periodic waves when it compares with the case of no resonance system. Further, it was found that there is the optimal width of a wave resonator to attenuate the target solitary waves.

The propagation of nonlinear waves in field-effect transistors with quantum effects

Zhang Liping,Yang Yunqing,Feng Jiangxu,Zhang Meilin 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.85 No.5

Shock and solitary waves are very important nonlinear structure in the channel of feld-efect transistors (FET). In this paper, the propagation of shock and solitary waves with quantum efects in the channel of FET is investigated. Using reductive perturbation expansion, the quantum hydrodynamic equations are reduced to KdV–Burgers and KdV equations describing the characteristic of shock and solitary waves with quantum efects in the channel of FET. The analytical and numerical results show that there are two diferent types of shock waves and solitary waves in this system; the monotone shock waves, the oscillatory waves and the solitary waves can transform each other under certain condition; the quantum efects strengthened shock waves oscillation and change the width of the solitary waves. This fnding provides a new idea for fnding efcient THz radiation sources and opens up a new mechanism for the development of THz technology.

쇄파가 수중 수평판의 고립파 제어에 미치는 영향

이우동(Woo-Dong Lee),이상엽(Sang-Yeop Lee),정영한(Yeong-Han Jeong),박종률(Jong-Ryul Park)허동수(Dong-Soo Hur) 한국연안방재학회 2021 한국연안방재학회지 Vol.8 No.1

A numerical analysis was performed to analyze the solitary wave control mechanism of a submerged horizontal plate (SHP). A two-dimensional numerical wave tank (NWT), which uses a wave generation method that generates a stable solitary wave, was employed for the numerical analysis. To verify the effectiveness of the NWT, the waveform measured around the SHP was compared to the calculated waveform. Moreover, the approximate and the calculated waveforms were compared in order to examine whether the solitary wave was stably generated. The results of comparison and verification showed that the deformation of the solitary wave by SHP was reproduced with high accuracy in the calculation, while the calculated waveform of NWT also showed a high degree of matching with the approximate waveform. The solitary wave breaking on the SHP satisfied the existing threshold condition A 0 /h c > 0.827-0.833, but breaking did not occur even under the condition A 0 /h c =1.2 when the width of the SHP was small. Accordingly, the wave height attenuation of the solitary wave occurred rapidly in a breaking condition. In a non-breaking condition, the energy gradually decreased due to the vorticity and turbulence around the boundary of the SHP, resulting in a gradual attenuation of the solitary wave.

Sluice Gate를 이용한 고립파 발생조건에 따른 형상 및 압력 특성에 관한 실험적 연구

조재남 ( Jae Nam Cho ),김동현 ( Dong Hyun Kim ),이승오 ( Seung Oh Lee ) 한국안전학회(구 한국산업안전학회) 2016 한국안전학회지 Vol.31 No.2

Recently, coastal erosion has been widely in progress and the erosion level becomes also serious in the world wide, espeically in East Sea in Korea. Since it would threaten the life, economics and security risk, it is necessary to much comprehend the reason why coastal erosion has occurred according to the geographical characteristics. Meanwhile, analysis about hydrodynamics of the solitary wave such as tunami in swash zone is needed for the best management practice of coastal erosion. Solitary wave is nonlinear wave and can be reproduced in the laboratoy scale by openning suddenly a sluice gate with water head difference, of which methodology was found in the literature, since it could be simply determined by a significant wave height. Thus, in this sutdy the generation of solitary wave was experimentalized using the sluice gate. Experimental conditions were classified by angles of a beach slope, a water level in a beach slope and a difference of water level between in a headtank and a channel bed. Two kinds of dimensionless analyses based from experimental results in this study were presented; the first analysis indicates nondimensionalization between the wave height and the water level in a beach slope in order to investigate characteristics of solitary wave approaching the beach. The second shows the other nondimensionalization between dynamic pressure and static pressure on a beach slope to investigate the relationship between wave breaking and wave pressure. Under the same conditions as laboratory experiments, the numerical results computed with a SWAN model embedded in FLOW 3D were compared in terms of wave height, and pressure on the beach slope, which shows good agreement with each other. Overall results from this study could provide fundamental hydraulic data for the reliabile verification of numerical simulation results about coastal erosion in swash zone caused by solitary waves.

Head-on Collision Between Two Envelope Solitary Waves in a Granular Medium

Wen-Qing Du,Jian-An Sun,Juan-Fang Han,Wen-Shan Duan,Yang-Yang Yang,Xin Jiang 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.11

We investigated the head-on collision between two envelope solitary waves. Head-on collisions between two envelope solitary waves are first discussed in one-dimension (1D) granular chains. The interesting result is that no phase shift or phase delay detected after the head-on collision between two envelope solitary waves. The maximum amplitude during the head-on collision between two envelope solitary waves is also found to be less than the sum of the amplitudes of the two envelope solitary waves, but is larger than the amplitude of the either of the envelope solitary waves.

Modeling of Modified Electron-acoustic Solitary Waves in a Relativistic Degenerate Plasma

M. R. Hossen,A. A. Mamun 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.12

The modeling of a theoretical and numerical study on the nonlinear propagation of modifiedelectron-acoustic (mEA) solitary waves has been carried out in an unmagnetized, collisionless, relativistic,degenerate quantum plasma (containing non-relativistic degenerate inertial cold electrons,both non-relativistic and ultra-relativistic degenerate hot electron and inertial positron fluids, andpositively-charged static ions). A reductive perturbation technique is used to derive the planar andthe nonplanar Korteweg-de Vries (K-dV) equations, which admit a localized wave solution for thesolitary profile. The solitary wave’s characteristics are found to have been influenced significantlyforin the non-relativistic and the ultra-relativistic limits. The mEA solitary waves are also foundto have been significantly modified due to the effects of the degenerate pressure and the numberdensities of this dense plasma’s constituents. The properties of the planar K-dV solitary wave arequite different from those of the nonplanar K-dV solitary wave. The relevance of our results toastrophysical objects (like white dwarfs and neutron stars), which are of scientific interest, is brieflymentioned.

수리/수치파동수조에서 안정적인 쓰나미 조파를 위한 고찰

이우동,박종률,전호성,허동수 대한토목학회 2016 대한토목학회논문집 Vol.36 No.5

본 연구에서는 쓰나미에 대응할 수 있는 다양한 파형의 고립파를 수리/수치파동수조에서 안정적으로 생성시키기 위하여 기존의 고립파 근사이론에 관한 검토를 수행하였다. 그리고 이 근사이론식을 토대로 다양한 고립파의 파형을 추정할 수 있는 두 가지 방법을 제안하였다. 이 방법들은기존의 고립파 근사식들을 토대로 파형분포조절계수와 가상수심계수를 적용하여 다양한 파형 및 유속을 추정하는 절차를 거친다. 새롭게 제안한 고립파 추정방법들을 수리/수치파동수조의 조파에 적용하였다. 그 결과, 수리파동수조에서는 조파기의 위치정보신호를 추정할 수 있을 뿐만아니라, 기존의 수리모형실험의 입력신호와 매우 유사한 것을 확인할 수 있었다. 수치파동수조에서는 파랑을 생성하기 위하여 고립파의 파형 및유속을 적용하였다. 그리고 기존의 고립파 근사이론으로는 재현할 수 없었던 쓰나미의 파형을 조파할 수 있었고, 기존 실험결과와 높은 일치도를 나타내는 것을 확인할 수 있었다. 이로써 수리/수치파동수조에서 안정적인 쓰나미를 생성하기 위하여 제안한 두가지 추정방법의 타당성 및유효성을 확인할 수 있었다. This study considered the existing approximation theories of solitary wave for stable generation of it with different waveforms in ahydraulic/numerical wave tank for coping with the tsunami. Based on the approximation theory equations, two methods wereproposed to estimate various waveforms of solitary wave. They estimate different waveforms and flow rates by applying waveformdistribution factor and virtual depth factor with the original approximate expressions of solitary wave. Newly proposed estimationmethods of solitary wave were applied in the wave generation of hydraulic/numerical wave tank. In the result, it was able to estimatethe positional information signal of wave generator in the hydraulic wave tank and to find that the signal was very similar to an inputsignal of existing hydraulic model experiment. The waveform and velocity of solitary wave was applied to the numerical wave tank inorder to generate wave, which enabled generate waveform of tsunami that was not reproduced with existing solitary waveapproximation theory and found that the result had high conformity with existing experiment result. Therefore, it was able to validateand verify the two proposed estimation methods to generate stable tsunami in the hydraulic/numerical wave tank.

Numerical investigation of solitary wave interaction with a row of vertical slotted piles on a sloping beach

Changbo Jiang,Xiaojian Liu,Yu Yao,Bin Deng 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

To improve our current understanding of tsunami-like solitary waves interacting with a row of vertical slotted piles on a sloping beach, a 3D numerical wave tank based on the CFD tool OpenFOAM® was developed in this study. The Navier-Stokes equations were employed to solve the two-phase incompressible flow, combining with an improved VOF method to track the free surface and a LES model to resolve the turbulence. The numerical model was firstly validated by our laboratory measurements of wave, flow and dynamic pressure around both a row of piles and a single pile on a slope subjected to solitary waves. Subsequently, a series of numerical experiments were conducted to analyze the breaking wave force in view of varying incident wave heights, offshore water depths, spaces between adjacent piles and beach slopes. Finally, a slamming coefficient was discussed to account for the breaking wave force impacting on the piles.

수면 위에서 병진 운동하는 압력에 의해 발생하는 중력-표면장력 비선형 파동

조연우(Yeunwoo Cho) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

Water-wave patterns generated by a pressure forcing moving with speeds close to the minimum phase speed (c<SUB>min</SUB>=23 ㎝/s) are investigated experimentally and theoretically. Four different behavioral states are observed according to forcing speeds and two transitional speeds are identified in the subcritical speed ranges. For speeds which are less than 22 ㎝/s, the patterns are simply locally depressed linear waves. For speeds between 22 and 23 ㎝/s, there exists a first transition speed, above which steady 3-D gravity-capillary solitary waves behind the forcing are observed. For speeds which are very close to c<SUB>min</SUB>=23 ㎝/s, a second transition is identified, where a periodic shedding of 3-D gravity-capillary solitary waves is observed. Finally, for speeds larger than 23 ㎝/s, a V-shaped linear wave pattern is observed. This work is an excerpted version of the present author’s past publications <SUP>(1),(2),(3)</SUP>, a part of which was also published in the Proceedings of the 7<SUP>th</SUP> National Congress on Fluids-Engineering.