共查询到16条相似文献,搜索用时 109 毫秒
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本文运用二体碰撞近似理论研究了孤波在周期型二元颗粒链中的传播. 周期型二元颗粒链由N个大球和一个小球交替排列而成, 球的材质都相同. 将小球和与之相邻的大球等效成一个球, 形成一条等效链. 采用二体碰撞近似理论, 推导了孤波在颗粒链中传播的速度、通过颗粒链时间以及小球的振荡频率. 理论分析得到小球振荡频率随着半径的增大而减小, 该结果与计算机模拟结果符合得相当好. 二体碰撞近似理论给出的波通过整条颗粒链时间, 在N ≤ 2时与计算机模拟结果符合得很好. 理论计算的误差随链长的变化不大. 但随着N的增大, 理论得到的结果相对误差变大. 相似文献
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以南中国海东北部海域底部缓坡地形为背景, 在大型重力式分层流水槽中模拟了下凹型内孤立波沿缓坡地形传播过程中的浅化、破碎、分裂等现象, 利用分层染色标识方法和多点组合探头阵列技术对内孤立波沿缓坡地形演化特征进行了定性分析和定量测量. 实验表明: 浅化效应使内孤立波传播速度减小, 对大振幅内孤立波具有抑制作用, 对小振幅波具有放大效应; 浅化效应可导致内孤立波的剪切失稳及破碎, 还可导致大振幅内孤立波的分裂. 利用Miles稳定性理论可定性描述内孤立波沿缓坡地形传播时发生不稳定状态的位置, 实验结果与理论分析相符合.
关键词:
分层流
缓坡地形
内孤立波
不稳定性 相似文献
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利用积分因子法对非均匀圆柱壳中传播孤立波的动力学稳定性进行详细的数值研究.以高斯波扰动、简谐波扰动和随机扰动作为初始扰动,考察受到这三种不同扰动的孤立波能否较长时间保持波形结构和传播速度而稳定传播的问题.结果表明:孤立波的稳定传播与扰动幅度、宽度和波长有关,只在受到幅度、宽度和波长都足够小的扰动下非均匀圆柱壳中传播的孤立波才能够表现出较强的抗干扰性,具有良好的动力学稳定性. 相似文献
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内孤立波在海洋中广泛存在,其在生成、传播演化以及耗散过程中对海洋环境、地形地貌和海洋结构物等有着深远的影响.针对内孤立波理论模型研究,已有理论模型包括单向传播Korteweg-de Vries (KdV)类方程和双向传播Miyata-Choi-Camassa (MCC)类方程,然而,两类方程均未能有效地模拟大振幅内孤立波的传播演化过程.本文采用渐近匹配方法,对原始单向传播内孤立波方程的系数进行修正,建立了改进的单向传播内孤立波理论模型.在此基础上,通过比较分析改进了前后内孤立波的理论模型,结果表明,改进后的理论模型稳态内孤立波的理论极限振幅能达到MCC方程稳态内孤立波的理论极限振幅.结合系列实验结果,通过定量分析稳态内孤立波有效波长、波速和波形与MCC方程稳态内孤立波理论解的吻合度,进一步分析了改进后的内孤立波理论模型在表征定态内孤立波特性方面的适用性.此外,针对平坦地形条件下大振幅内孤立波非定态传播演化过程,探究各类单向传播孤立波理论模型的稳定性.研究表明改进后高阶单向传播内孤立波理论模型可用于表征大振幅内孤立波传播演化特性,为海洋结构物水动力学研究提供理论依据. 相似文献
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In a step-down chain a solitary wave (SW) evolves into an SW train (SWT), but the formation of well-defined SWT takes time and space and little is known of the process from immature into mature SWT. We therefore perform a detailed numerical study of this process by analysing the local velocity amplitude and peak overlap of immature ordered SWs. The first SW continuously increases to maximal velocity amplitude and peak overlap until it is matured, but for following SWs there exist a minimal and maximal value of local velocity amplitude and, a minimal and maximal value of local peak overlap, clarifying the details of the energy propagation along the stepped chain. The immature and mature SWTs show the same dependence of the phase velocity on the SWs sequence. These provide guidelines for when or where the attention should be paid in the study of SWT. 相似文献
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We implement a binary collision approximation to study solitary wave propagation in a two-dimensional double Y-shaped granular chain. The solitary wave was transmitted and reflected when it met the interface of the bifurcated branches of the Y-shaped granular chains. We obtain the analytic results of the ratios of the transmitted and reflected speeds to the incident speed of the solitary wave, the maximum force between the two neighbor beads in a solitary wave, and the total time taken by the pulse to pass through each branch. All of the analytic results are in good agreement with the experimental observations from Daraio et al. [Phys. Rev. E 82 036603 (2010)]. Moreover, we also discuss the delay effects on the arrival of split pulses, and predict the recombination of the split waves traveling in branches in the final stem of asymmetric systems. The prediction of pulse recombination is verified by our numerical results. 相似文献
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We numerically investigate the nonlinear waves propagating in a one-dimensional particle chain when the damping effect is taken into account. It is found that decaying solitary waves exist, in which the amplitude of the wave decreases exponentially as time increases. Meanwhile, the velocity of the solitary wave also slows down as time goes. This result implies that the damping coefficient is an important parameter in such a nonlinear system. Theoretical analysis has also been done by the reductive perturbation method. The result indicates that the nonlinear waves propagating in such a system can be described by the damped KdV equation. 相似文献
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The Gross--Pitaevskii equation which describes the motion of a Bose--Einstein
condensed (BEC) atom in an elongated trap is solved analytically, and a solitary-wave solution
is obtained in the low-density case without neglecting the effect of the interatomic
interaction on the transverse function. It is shown that this effect leads to
the velocity of the solitary wave slowing down and the profile
of the solitary wave widening. 相似文献
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针对三维浅海环境下孤立子内波对低频声信号传播特性的影响问题,基于Oxyz坐标系下的三维浅海低频声场有限元计算方法,以声能流为研究对象,仿真分析了内波存在对低频声信号传播特性的影响规律。研究结果表明:受内波影响,在xOz平面,声能流垂直分量的传播偏转角度呈现周期性的起伏规律;随着声源深度的增加,内波对声能流偏转角度的影响深度也随之增加。对xOy平面,当声源位于温跃层以上时,随着接收深度的增加,各深度平面上声能流水平分量的偏转角越大;随着声源深度的增加,内波对各深度平面上声能流的影响逐渐减弱。 相似文献