共查询到20条相似文献，搜索用时 187 毫秒
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利用高阶边界元方法求解拉普拉斯方程,建立了模拟完全非线性聚焦波的时域数值模型,其中追踪流体自由表面的方法为满足完全非线性自由水面条件的半混合欧拉-拉格朗日方法,运用四阶Runga-Kutta方法计算每一时间步新的波面高度和速度势,同时通过入射边界给定速度的二阶Stokes解析解产生波浪,并应用镜像格林函数消除水槽两个侧面和底面上的积分。对不同波陡的聚焦波群在水槽中开展了物理模型实验,并把试验结果和数值结果进行了对比,两者吻合得很好,然后对非线性条件下聚焦波的特点进行了研究。 相似文献
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目前针对波浪作用下海底盾构隧道周围渗流场的既有理论研究一般将衬砌考虑为不透水介质,较少考虑隧道衬砌的渗透性,尤其是较少考虑海底斜坡地形下波浪非线性带来的影响。首先基于斜坡海床表面的动力边界条件,得到Stokes非线性波作用下自由海床的Biot固结孔压响应;其次,采用镜像法建立了由于隧道存在引起的砂土体摄动压力控制方程,并利用砂土与衬砌间渗流连续条件获得了该方程的Fourier级数展开解析解;接着,采用叠加原理得到了Stokes波作用下斜坡海床中隧道周围砂土的渗流压力响应解答;最后,将理论解析解与数值结果及已有的试验结果进行对比,获得了较好的一致性。此外,针对波浪敏感参数(波长、周期、形态)、海床敏感参数(海床渗透性、剪切模量、饱和度、坡度)及隧道敏感参数(衬砌厚度、渗透性、埋深)进行了影响因素分析。结果表明：随着波浪周期及波长增加,衬砌外超静孔压明显增加;随着水深沿斜坡方向减小,Airy波和Stokes波理论在适用范围内(d/L>0.125,d为海水深度,L为波长),获得的波浪压力差异明显增加,前者会低估隧道周围的超静孔隙水压力;当海床渗透系数较大时(ks&... 相似文献
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建立了基于高阶Boussinesq水波方程的一维波浪破碎数值模型。基于一组具有二阶完全非线性特征的Boussinesq水波方程,建立了交错网格下的高精度差分格式,推导了适用于该组方程的永形波解析解,其和松弛造波技术相结合实现了数值波浪水槽中(强)非线性波浪的无反射入射。通过模拟封闭容器内水体晃动问题对数值格式进行了验证,通过模拟孤立波在斜坡海岸上的浅化过程说明了将方程从弱非线性发展到完全非线性的必要性。采用涡粘方法处理波浪破碎,利用物理模型实验数据,分析了模型中各波浪破碎参数对数值结果的影响并对参数进行了率定。应用该模型对规则波在斜坡海岸上的传播、变浅以及破碎过程进行了数值模拟研究,数值结果同实验数据吻合良好,验证了模型的有效性。 相似文献
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为了更好地研究近岸海域波生沿岸流,建立了基于高阶Boussinesq水波方程的波生沿岸流时域数值模型。控制方程在中等水深范围内具有较好的色散性和变浅作用性能,同时具有二阶完全非线性特征,适合描述近岸区域波浪强非线性运动。通过采用松弛造波方法实现了非线性波浪的无反射入射,采用周期性侧边界条件模拟开敞边界。通过数值试验,讨论了模型中主要参数对数值结果的影响。利用率定后的参数模拟了均匀坡度海岸上产生的沿岸流,通过和实验数据的对比验证了模型的准确性和适用性。利用模型数值模拟了不同波浪入射条件(包括周期、波高和波浪入射角度)对波生沿岸流的影响。 相似文献
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《岩土力学》2021,(2)
为研究强降雨条件下地表径流和裂隙水流的拖曳力作用对斜坡稳定性的影响,建立斜坡地表径流和地下水渗流耦合分析模型。采用Navier–Stokes方程描述地表径流和裂隙水流,Brinkman-extended Darcy方程描述土体和岩石中的渗流,并根据不同介质交界面处流速相等及剪应力连续的边界条件,推求各个介质中的流速分布。应用Newton内摩擦定律求得水流对斜坡产生的拖曳力,进而将拖曳力嵌入刚体极限平衡理论对斜坡稳定性进行分析。典型斜坡实例计算结果表明,当未考虑拖曳力效应时,斜坡的安全系数为1.164,考虑水流对斜坡土体产生拖曳力效应时,斜坡的安全系数为1.089,斜坡安全系数降低了6.44%。这表明拖曳力作用对斜坡的稳定性存在不利影响,斜坡土体在近乎临界稳定状态下拖曳力将对斜坡失稳起到决定性作用。最后分别讨论了考虑拖曳力和不考虑拖曳力情况下斜坡的安全系数与径流水深、斜坡倾角、土层厚度之间的关系。 相似文献
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《岩土力学》2020,(2)
为研究强降雨条件下地表径流和裂隙水流的拖曳力作用对斜坡稳定性的影响,建立斜坡地表径流和地下水渗流耦合分析模型。采用Navier–Stokes方程描述地表径流和裂隙水流,Brinkman-extended Darcy方程描述土体和岩石中的渗流,并根据不同介质交界面处流速相等及剪应力连续的边界条件,推求各个介质中的流速分布。应用Newton内摩擦定律求得水流对斜坡产生的拖曳力,进而将拖曳力嵌入刚体极限平衡理论对斜坡稳定性进行分析。典型斜坡实例计算结果表明,当未考虑拖曳力效应时,斜坡的安全系数为1.164,考虑水流对斜坡土体产生拖曳力效应时,斜坡的安全系数为1.089,斜坡安全系数降低了6.44%。这表明拖曳力作用对斜坡的稳定性存在不利影响,斜坡土体在近乎临界稳定状态下拖曳力将对斜坡失稳起到决定性作用。最后分别讨论了考虑拖曳力和不考虑拖曳力情况下斜坡的安全系数与径流水深、斜坡倾角、土层厚度之间的关系。 相似文献
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深层岩体松动爆破中不耦合装药效应的探讨 总被引：2，自引：0，他引：2
基于冲击波在交界面两侧压力和速度必须各自相等的连续性条件,求解爆轰产物中适用的反射波方程和介质中适用的冲击波方程,得到药包周围介质中冲击波的初始参数.通过波的传播机理,把集中药包应力波随距离的衰减公式扩展到延长药包,并计算耦合与不耦合装药爆破时距爆心相同距离处岩石中冲击波的参数.由计算结果可知:(1)耦合装药爆破时形成的冲击波压力超过岩石抗压强度极限几十倍以上,药包周围岩石形成粉碎区;(2)与耦合装药爆破相比,不耦合装药爆破可以降低孔壁处岩石中冲击波初始压力,但可以增加孔壁后岩石中的冲击波压力.合理的不耦合系数,可使岩石不形成粉碎区,大幅度减少能量耗散;(3)水一般认为是非线性弹性介质,因此水介质成为炸药爆轰产物与岩石间的弹性缓冲层,增加了能量传递,延长了冲击波作用时间,加大了爆炸的作用范围. 相似文献
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This study addresses the impact of nonlinear wave evolution on the resulting wave force values on a vertical wall. To this end, the problem of interaction between non-breaking water waves and a vertical wall over constant depth is investigated. The investigation is performed using a two-dimensional wave flume model which is based on the high-order spectral method. Wave generation is simulated at the flume entrance by means of the additional potential concept. This model enables to preserve full dispersivity. Therefore, the model enables to examine the role of nonlinear evolution in the formation of extreme wave force values on a vertical wall for a wide range of water depths. The results for the force exerted on a vertical wall are presented for shallow and deep water conditions. In shallow water, extreme wave force values occur due to the formation of an undular bore. In deep water, extreme wave forces have been obtained as a result of disintegration process of incident wave groups into envelope solitons. Multiple maximum force values have been detected for each of the highest run-up peaks. This phenomenon has been introduced in shallow water conditions and is extended here for deep water conditions. 相似文献
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Comparison of linear and nonlinear shallow wave water equations applied to tsunami waves over the China Sea 总被引：4，自引：0，他引：4
Yingchun Liu Yaolin Shi David A. Yuen Erik O. D. Sevre Xiaoru Yuan Hui Lin Xing 《Acta Geotechnica》2009,4(2):129-137
This paper discusses the applications of linear and nonlinear shallow water wave equations in practical tsunami simulations.
We verify which hydrodynamic theory would be most appropriate for different ocean depths. The linear and nonlinear shallow
water wave equations in describing tsunami wave propagation are compared for the China Sea. There is a critical zone between
400 and 500 m depth for employing linear and nonlinear models. Furthermore, the bottom frictional term exerts a noticeable
influence on the propagation of the nonlinear waves in shallow water. We also apply different models based on these characteristics
for forecasting potential seismogenic tsunamis along the Chinese coast. Our results indicate that tsunami waves can be modeled
with linear theory with enough accuracy in South China Sea, but the nonlinear terms should not be neglected in the eastern
China Sea region. 相似文献
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破碎区至冲泻区水动力特性分析是研究近岸地区泥沙输运机理和岸滩演变的关键。考虑潜堤修建的影响,对破碎区至冲泻区水动力特性开展研究。运用基于RANS方程的波浪数学模型,选取非线性涡粘性κ-ε紊动传输模型,采用高精度PLIC-VOF方法追踪自由面,并用实验数据验证模型精度。计算分析结果表明,潜堤的修建改变了破波点的位置,破碎区至冲泻区内水动力特性随之变化,入射波波高H、波长L、堤顶水深R和堤顶宽度B是主要影响因素。在相同的入射波条件下,B/R增大,破碎区至冲泻区内出现的最大紊动动能值和最大紊动耗散值减小。用量纲一参数Re,Fr和St来描述破碎区至冲泻区水动力特性,随着RL/BH增大,波浪将在离岸较近处发生破碎,Re和Fr增大,St减小。 相似文献
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A rigorous finite volume model to simulate subaerial and submarine landslide-generated waves 总被引：5，自引：5，他引：0
This paper presents a new landslide-generated wave (LGW) model based on incompressible Euler equations with Savage-Hutter assumptions. A two-layer model is developed including a layer of granular-type flow beneath a layer of an inviscid fluid. Landslide is modeled as a two-phase Coulomb mixture. A well-balanced second-order finite volume formulation is applied to solve the model equations. Wet/dry transitions are treated properly using a modified non-linear method. The numerical model is validated using two sets of experimental data on subaerial and submarine LGWs. Impulsive wave characteristics and landslide deformations are estimated with a computational error less than 5 %. Then, the model is applied to investigate the effects of landslide deformations on water surface fluctuations in comparison with a simpler model considering a rigid landslide. The model results confirm the importance of both rheological behavior and two-phase nature of landslide in proper estimation of generated wave properties and formation patterns. Rigid slide modeling often overestimates the characteristics of induced waves. With a proper rheological model for landslide, the numerical prediction of LGWs gets more than 30 % closer to experimental measurements. Single-phase landslide results in relative errors up to about 30 % for maximum positive and about 70 % for maximum negative wave amplitudes. Two-phase constitutive structure of landslide has also strong effects on landslide deformations, velocities, elongations, and traveling distances. The complex behaviors of landslide and LGW of the experimental data are analyzed and described with the aid of the robust and accurate finite volume model. This can provide benchmark data for testing other numerical methods and models. 相似文献
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从双程声波方程出发,在交错网格空间中推导了地震波逆时延拓的高阶有限差分算子,依据最佳匹配层(PML)的方程分裂思路,得到了一阶声波方程的PML边界条件及其高阶差分格式,采用零时间成像条件和上行、下行波场互相关成像条件,实现了声波方程的叠后与叠前逆时深度偏移。逆时偏移对sigsbee_2b模型理论数据的偏移成像得到了满意效果。 相似文献
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基于波作用量守恒方程建立了波流共存场中多向随机波浪传播变形数学模型,模型中考虑了波浪绕射的影响和水流引起的波浪弥散多普勒效应,应用包含水流和地形影响的激破波模式计算波浪破碎的能量耗散,采用一阶上迎风有限差分格式离散控制方程。分别计算了有无近岸流情况下单向和多向随机波浪的波高分布,考虑水流影响的数值计算结果与物理模型实验数据吻合良好,比较分析表明,所建立的数学模型能够复演由于离岸流引起的波高增大,可用于波流共存场多向随机波浪传播变形的模拟和预报。 相似文献
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Duan W. Y. Zheng K. Zhao B. B. Demirbilek Z. Ertekin R. C. Webster W. C. 《Natural Hazards》2016,84(2):567-583
This work is on the use of the Green–Naghdi (GN) nonlinear wave equations for simulating wave–current interaction in shallow water. The stream-function wave theory is used at the wave-maker boundary to generate nonlinear incident waves to consider the wave–current interaction. The nonlinear GN equations are solved in the time domain by use of the finite-difference method. The model is evaluated with data from three experimental studies. A strong opposing current over a submerged bar is investigated in the first test case. In the second test case, the interaction of waves with a uniform current over flat bottom is considered. In the third case, wave–current interaction over a variable bathymetry with the following and opposing currents is studied. The numerical results obtained by the GN equations are compared with the experimental data and results based on the Boussinesq equations. A good agreement is obtained for the three experimental studies considered for a wide range of wave and current conditions. 相似文献
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桩-土相互作用问题是岩土工程桩基础问题的关键点与难点,目前针对桩身在循环温度荷载与上覆结构荷载双重作用下的能源桩承载特性研究较少。在传统理想弹塑性模型及双曲线模型的基础上,采用分段非线性的方法对桩-土荷载传递骨干曲线进行了修正,并基于Masing’s循环准则,提出了适用于能源桩的桩-土荷载传递模型。利用改进的桩-土荷载传递模型对能源桩承载特性进行数值分析,着重研究了桩-土荷载传递参数比R对能源桩受力情况的影响。此外,为了探究在上覆结构荷载及循环温度荷载双重作用下,能源桩与周围土体之间的真实荷载传递关系及其结构热力学特性,开展了针对能源桩与周围土体之间相互作用问题的室内模型试验,监测了其桩身轴向应力及侧摩阻力随温度及深度变化的趋势,并与基于改进荷载传递模型的数值计算结果进行了对比。室内模型试验监测及数值计算结果显示：能源桩在上覆结构荷载及温度循环荷载双重作用下,其受力行为受改进的桩-土荷载传递循环曲线控制;基于改进的桩-土荷载传递循环曲线而建立的数值模型计算结果与试验结果基本吻合,改进的桩-土荷载传递模型能够较好发地反映能源桩实际的承载特性。 相似文献
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Mathematical simulation of non‐isothermal multiphase flow in deformable unsaturated porous media is a complicated issue because of the need to employ multiple partial differential equations, the need to take into account mass and energy transfer between phases and because of the non‐linear nature of the governing partial differential equations. In this paper, an analytical solution for analyzing a fully coupled problem is presented for the one‐dimensional case where the coefficients of the system of equations are assumed to be constant for the entire domain. A major issue is the non‐linearity of the governing equations, which is not considered in the analytical solution. In order to introduce the non‐linearity of the equations, an iterative discretized procedure is used. The domain of the problem is divided into identical time–space elements that cover the time–space domain. A separate system of equations is defined for each element in the local coordinate system, the initial and boundary conditions for each element are obtained from the adjacent elements and the coefficients of the system of equations are considered to be constant in each step. There are seven governing differential equations that should be solved simultaneously: the equilibrium of the solid skeleton, mass conservation of fluids (water, water vapor and gas) and energy conservation of phases (solid, liquid and gas). The water vapor is not in equilibrium with water and different phases do not have the same temperature. The governing equations that have been solved seem to be the most comprehensive in this field. Three examples are presented for analyzing heat and mass transfer in a semi‐infinite column of unsaturated soil. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献