共查询到19条相似文献，搜索用时 343 毫秒
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利用特征函数展开法对台阶式变深水槽中推板式造波机造波问题进行了研究，建立了相应速度势和波面的解析表达式。与高阶边界元方法(HOBEM)数值结果进行了对比，验证了本解析解的正确性。通过数值试验，研究了台阶对入射波的影响，同时分析了造波板所在位置（上部台阶）水深、水槽工作区（下部台阶）水深、造波板运动周期和造波板水平位置等因素对生成波浪高度的影响。由此选择合适的造波板所在位置及水深来得到所需要的波浪高度，进而根据需要生成波浪的周期和波幅 来反演造波板的运动。 相似文献
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应用基于势流理论的时域高阶边界元方法,建立一个完全非线性的三维数值波浪水槽,通过实时模拟推板造波运动的方式产生波浪。通过混合欧拉-拉格朗日方法和四阶Runge-Kutta方法更新自由水面和造波板的瞬时位置。利用所建模型分别模拟了有限水深波和浅水波,与试验结果、相关文献结果和浅水理论结果吻合较好,且波浪能够稳定传播。系统地讨论造波板的运动圆频率、振幅和水深等对波浪传播和波浪特性的影响,并对波浪的非线性特性进行分析,研究发现造波板运动频率、运动振幅以及水深均将对波浪形态和波浪非线性产生显著影响。结果为真实水槽造波机的运动控制以及波浪生成试验提供了依据,便于实验室设置更合理的参数来准确模拟不同条件下的波浪。 相似文献
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波浪水槽中非线性浅水波传播特性与模拟 总被引：2，自引：0，他引：2
通过建立解析解、进行数值模拟和物理实验，研究了波浪水槽中非线性浅水波浪传播特性，给出了数值模拟中对应造波板做正弦运动的二阶入射边界条件。数值模拟采用高阶Boussinesq方程。实验结果、数值结果和解析解进行对比，并讨论了解析解的适用范围、高次谐波的产生及三波相互作用问题。 相似文献
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利用完全非线性数值波浪水槽技术研究水下平板与波浪的相互作用。假定水下平板厚度极薄、刚性,位于有限水深并且非常接近自由水面。应用四阶龙格库塔方法追踪每一时刻的波面形状,采用阻尼层来吸收反射波以保证算法的稳定性,同时引入平滑和重组的方法抑制自由表面控制点的较高梯度。通过对波浪与浮动圆柱相互作用的数值模拟证实了数值波浪水槽方法的有效性,计算结果与线性理论吻合良好。在波浪数值水槽方法中引入造波板模拟波浪产生并与水下平板发生相互作用,应用傅立叶解析方法对波面变形、波浪力作了分析。结果表明在板非常接近自由水面的情况下会表现出现很强的非线性,揭示了线性理论的局限性。 相似文献
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基于推板造波理论和摇板造波理论,在Open FOAM平台上采用重叠网格技术建立黏性数值波浪水槽,并使用一种结合SIMPLE算法和PISO算法的PIMPLE算法对数值模型进行求解。利用开发的数值模型通过数值收敛性测试和网格独立性测试分别重点研究了时间步长、库朗数和网格尺寸对数值精度和计算效率的影响。并对比研究了此数值模型分别嵌入层流模型和湍流模型的计算精度和计算效率。实现的规则波和二阶有限振幅波与理论结果和试验结果吻合,验证了此黏性数值波浪水槽的造波和主动消波功能。基于二维数值波浪水槽,进一步研究了三维数值造波,数值计算结果与理论结果吻合良好。研究结果不仅验证了重叠网格在二维和三维两相流体域中求解运动物体与流场交互的可靠性和正确性,而且为使用此黏性数值波浪水槽解决更复杂的海洋工程问题提供了依据。 相似文献
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当波浪由外海向跨海桥梁所在的近岸海域传播时,随着水深急剧变浅,波浪会发生破碎。强非线性的破碎波会给桥墩结构带来极大冲击作用。基于计算流体力学(CFD)数值软件Flow-3D建立三维数值水槽,造波边界设为斯托克斯五阶波。通过在数值水槽中建立逐渐浅化的三维地形,采用k-ω湍流模型求解雷诺平均N-S(RANS)方程,模拟破碎波冲击桥墩。与前人水槽试验及数值模拟结果进行比对,验证数值水槽的有效性。采用验证过的数值水槽,研究了不同入射波高和周期下的破碎波浪特性,计算了不同长宽比圆端形桥墩在不同入射波高的破碎波作用下受力和流场变化,讨论了最大压强作用点、准静态力和冲击力随桥墩长宽比的变化规律。研究表明:与前人试验和数值模拟相比,所建立的数值水槽具有较高精度;圆端形桥墩破波力随桥墩长宽比增大,先增大后趋于稳定,破波力峰值随着入射波高的增大而增大,同时,圆端形桥墩破波力峰值主要由冲击力控制。进行跨海桥梁圆端形桥墩设计时,应重点关注桥墩长宽比和破碎波冲击力的影响。 相似文献
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基于计算流体力学软件的三维数值模拟技术,分析了碟形越浪式波能发电装置的越浪性能,通过构建基于水气两相VOF(Volume of Fluid)模型的三维数值波浪水槽对该装置进行三维数值模拟研究,数值计算结果与物理试验结果相互对比验证较为吻合,验证了所构建的三维数值波浪水槽的可靠性,通过考察装置的坡度、导流叶片个数、干舷高度对越浪性能的影响确定装置的最优结构参数。结果表明,在装置的斜坡面边缘增加回流板可减少波浪的反射,提高装置的越浪性能。在数值模拟中将装置的斜坡面边缘处安装回流板对碟形越浪式波能发电装置参数进行优化,通过分析回流板的长度对装置越浪性能的影响来探索最优回流板长度。 相似文献
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内孤立波具有振幅尺度大、能量集中的特点,其引起流场和密度场的迅速变化可能对海洋工程结构物以及水下潜体造成严重威胁。因此研究不同造波条件下生成的内孤立波运动的流场特征具有重要的学术意义和实际应用价值。采用直接数值模拟方法和给定的初始密度场密度跃迁函数,对重力塌陷激发内孤立波的运动过程进行研究,探讨了不同造波条件下,激发产生的内孤立波波型、涡度、振幅和水平速度等流场特征。结果表明:(1)直接模拟数值方法能够模拟内孤立波传播过程中的密度界面波型反转现象;(2)从定性和定量的角度,证实了不稳定内孤立波传播过程中存在能量的向后传递;(3)对于相同的台阶深度(水闸两侧初始密度界面的高度差),初始涡流保持相同,但是随着上下层水深比的减小,其强度下降显著;(4)台阶深度对初始涡流的垂直结构的影响要大于上下层水深比,且台阶深度对内孤立波的振幅、水平速度的影响显著。 相似文献
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基于Boussinesq水波模型的聚焦波模拟 总被引：1，自引：1，他引：0
基于最高导数为3阶的单层Boussinesq方程,建立了聚焦波的时域波浪计算模型。数值模型求解采用了预报?校正的有限差分法。对于时间差分格式,预报和校正分别采用3阶Adams-Bashforth格式和4阶Adams-Moulton格式。首先,针对不同水深条件下水槽中传播的强非线性波进行模拟,并将数值结果与流函数的数值解析解进行了比较,结果表明无论是波面位移、波面处的水平速度和垂向速度均与解析解符合较好,最大波峰面的速度分布伴随水深的增加与解析解吻合程度变差,非线性速度分布的适用范围与线性解析解适应范围kh<3.5基本一致。其次,对深水聚焦波演化进行了模拟研究,研究中聚焦波的生成采用在边界点累加不同频率线性规则波的方法。应用聚焦波物理模型实验结果验证模型,计算聚焦位置处的波面位移和沿水深的速度分布与实验结果的对比表明,波面位移吻合程度较好,垂向的水平速度分布基本吻合。最后,保持中心频率(周期)不变,数值模拟了周期范围变化下最大聚焦波峰面以及波峰面水平速度的变化趋势,结果表明波峰面值和波峰面水平速度随着周期范围缩小而增大。 相似文献
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Comparative study on the accuracy of solitary wave generations in an ISPH-based numerical wave flume
In the present study, six solitary wave generations by different mathematical approximations are investigated using a piston type wave maker at dimensionless amplitudes ranging from 0.1 to 0.6 and two water depths. Incompressible smoothed particle hydrodynamics is used to simulate solitary wave propagation along the fixed depth channel. The present numerical results are compared with analytical results and experimental data in terms of free surface displacements, fluid particle velocity, phase speed, paddle motion, etc. The present mesh-free numerical results of wave profile variations over time proved that “Rayleigh” has the lowest relative wave height variation. However, its solitary wave has notable phase lead, while “Third order” and “Ninth order” have the least wave lags. Furthermore, the record of present numerical free surface elevation at different distances and the loss of amplitude of the main pulse showed that regarding both of them, “Ninth order” has supremacy over five others. Considering the numerical velocity components of generated solitary wave, “Third order” and “Ninth order” trace analytical results more accurately than other four ones, whereas “Rayleigh” is the most accurate one in predicting the maximum runup. Finally, the paddle motion, its velocity, and displacement, as well as phase speed and outskirts decay coefficient are also compared and discussed intensely. 相似文献
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Atilla Bayram 《Ocean Engineering》2000,27(4)
The aim of this study was to evaluate the performance of a sloping float (or inclined pontoon) breakwater with respect to expected wave climate for protection of small commercial vessels and yatch marinas. A two-dimensional model study was carried out for regular waves in intermediate water depths. The experimental results showed that the transmission coefficient was relatively insensitive to wave height and that it consistently increased as the wave period decreased. The performance of this type of breakwater was found to be promising for intermediate water depths. 相似文献
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旁靠带缆作业是实现海上补给、模块吊运、原油外输等运转的常用方式,针对浮式平台与两艘供应船以旁靠方式作业涉及的关键特征进行水池模型试验研究,阐述了旁靠带缆系统和护舷设备的属性和需遵循的规范衡准,深入分析旁靠系缆的张力、护舷的挤压力、船体之间的相对运动特征随有效波高和波浪入射角度等环境参数的变化规律,确定了适用于多船旁靠作业的海况条件。研究表明:波浪能量随有效波高的增大呈现非线性增大趋势,是影响旁靠作业窗口期的主要外部因素,而波浪入射角度对旁靠作业的影响程度与海况有较大关系;三船在纵荡、横荡以及艏摇方向具有明显的跟随性特点,运动响应的幅值和相位比较接近,浮式平台与供应船之间的相对运动较小,完全可满足作业要求。垂荡、横摇以及纵摇这三个波频方向,各船的运动并不同步,相对运动大,是影响多船旁靠作业窗口期的主要因素;有效波高为2.5 m的海况条件可满足多船旁靠要求。相关结论为实际的工程操作提供参考。 相似文献
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Experiments on silt incipient motion under wave action were carried out.Under wave action,for different wave periods,water depths and bulk densities of silt,the shear stress or height of waves for incipient motion was determined,and a relation between the shear stress and bulk density of silt was established.Results indicate that the critical shear stress depends on the structure of the silt itself,related to the tightness between the grains(or bulk density).Exterior condition is only an external cause of silt incipient motion,and the critical shear stress for the incipient motion is the token of exterior condition. 相似文献
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Based on rigid kinematics theory and lumped mass method,a mathematical model of the two net cages of grid mooring system under waves is developed.In order to verify the numerical model,a series of physical model tests have been carried out.According to the comparisons between the simulated and the experimental results,it can be found that the simulated and the experimental results agree well in each wave condition.Then,the forces on the mooring lines and the floating collar movement are calculated under different wave conditions.Numerical results show that under the same condition,the forces on the bridle ropes are the largest,followed by forces on the main ropes and the grid ropes.The horizontal and the vertical float collar motion amplitudes increase with the increase of wave height,while the relationship of the horizontal motion amplitude and the wave period is indistinct.The vertical motion amplitude of the two cages is almost the same,while on the respect of horizontal motion amplitude,cage B(behind cage A,as shown in Fig.4) moves much farther than cage A under the same wave condition.The inclination angle of the floating system both in clockwise along y axis and the counter one enlarges a little with the increase of wave height. 相似文献
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Underwater ultrasonic acoustic transducers are frequently used in ocean wave measurements as they measure surface level using acoustic waves. However, their effectiveness can be severely affected in rough sea conditions, when bubbles generated by breaking waves interfere with their acoustic signals. When the seas are rough, one therefore often has to rely on a pressure transducer, which is generally used as a back-up for the acoustic wave gauge. A pressure transfer function is then used to obtain the surface wave information. Alternatively, the present study employed an artificial neural network to convert the pressure signal into significant wave height, significant wave period, maximum wave height, and spectral peakedness parameter using data obtained from various water depths. The results showed that, for water depths greater than 20 m, the wave parameters obtained from the artificial neural network were significantly closer to those obtained by the acoustic measurements than those obtained by using a linear pressure transfer function. Moreover, for a given water depth, the wave heights estimated by the network model from pressure data were not as good as those estimated by linear wave theory for large wave heights (above a 4 m significant wave height in this study). This can be improved if the training data set has more records with large wave heights. 相似文献
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单桩基础周围斜坡海床中的波致孔隙水压力响应与纯斜坡海床存在较大差异。为了解不同波高、波周期条件下,单桩基础周围波浪传播变形及其对斜坡海床孔压振荡响应的影响,在波浪水槽末端铺设了长6 m、坡度1∶16的斜坡砂床进行试验。通过改变桩身位置和波浪参数,测量斜坡段各处波面形态,采集单桩周围孔隙水压力,分析了桩身位置及波浪参数对斜坡海床孔压响应的影响。结果表明：相同入射波条件下,随距坡脚水平距离增加,波高、近底流速和桩周孔隙水压力幅值都随之增大;桩周孔隙水压力幅值分布规律为：桩前孔压幅值明显大于桩侧与桩后孔压幅值。当Keulegan-Carpenter数大于6时,随着波高和波周期增大,马蹄涡产生的负压区使得桩侧海床孔隙水压力与纯斜坡海床孔隙水压力差值迅速增加。 相似文献