共查询到20条相似文献，搜索用时 31 毫秒
1.
Alekseev D. V. Dymova O. A. Miklashevskaya N. A. Cherkesov L. V. 《Physical Oceanography》2004,14(3):127-139
We present a survey of works carried out at the Wave-Theory Department of the Marine Hydrophysical Institute of the National Academy of Sciences of Ukraine for the last ten years and devoted to investigation of free and forced waves in bounded basins. Our attention is focused on the results of investigation of internal waves in basins of variable depth for the case of three-layer stratification of the liquid. The profiles of the bottom of the basin and interfaces are regarded as parabolic. Analytic solutions are obtained and the periods of oscillations of the free surface and interfaces for the first and second modes are determined. The dependences of the characteristics of baroclinic waves on the geometry of the basin and parameters of stratification are analyzed. 相似文献
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A Eulerian–Lagrangian method (ELM) is employed for the simulation of wave propagation in the present research. The wave action conservation equation, instead of the wave energy balance equation, is used. The wave action is conservative and the action flux remains constant along the wave rays. The ELM correctly accounts for this physical characteristic of wave propagation and integrates the wave action spectrum along the wave rays. Thus, the total derivative for wave action spectrum may be introduced into the numerical scheme and the complicated partial differential wave action balance equation is simplified into an ordinary differential equation. A number of test cases on wave propagation are carried out and show that the present method is stable, accurate and efficient. The results are compared with analytical solutions and/or other computed results. It is shown that the ELM is superior to the first-order upwind method in accuracy, stability and efficiency and may better reflect the complicated dynamics due to the complicated bathymetry features in shallow water areas. 相似文献
4.
Based on the filtered Navier-Stokes equations and Smagorinsky turbulence model,a numerical wave flume is developed to investigate the overtopping process of irregular waves over smooth sea dikes.Simulations of fully nonlinear standing wave and regular wave’s run-up on a sea dike are carried out to validate the implementation of the numerical wave flume with wave generation and absorbing modules.To model stationary ergodic stochastic processes,several cases with different random seeds are computed for each specified irregular wave spectrum.It turns out that the statistical mean overtopping discharge shows good agreement with empirical formulas,other numerical results and experimental data. 相似文献
5.
The present study originates from a construction problem found in the planned deployment of the side caissons of the Venice gates barrier. Each of these caissons is made to float, then sunk into a lateral trench and jointed to the soil at its bottom. As a result, a C-shaped channel forms between the vertical caisson surfaces and the surrounding trench. Incoming storm waves propagating from the sea can then induce forced oscillations in this C-channel. An analytical model based on the method of matched asymptotics is developed in order to obtain the free surface oscillations in the channel, caused by a grazing incident wave. The resonant response of the basin and the amplification factors are then determined. From the free surface elevation, the pressure field and hence the total forces are also found. The analysis moves on to irregular wave motion. The analytical solution enables us to compute the dynamic actions, showing that their magnitude can be significant, due to the excitation of different resonant modes. 相似文献
6.
We study forced long-wave oscillations of a liquid in a ring-shaped basin of variable depth within the framework of the linear theory of long waves with regard for the influence of the Coriolis force. The oscillations are induced by disturbances of atmospheric pressure periodic as functions of time. The parameters of the basin (bottom topography and linear sizes) are chosen to approximate the Antarctic region located between 60 and 70°S. The wave velocities and the structure of the modes of elevations of the free surface are determined by using numerical methods. We also establish the dependences of the characteristics of the wave process on the period of surface pressure. 相似文献
7.
The substructures of offshore wind turbines are subjected to extreme breaking irregular wave forces. The present study is focused on investigating breaking irregular wave forces on a monopile using a computational fluid dynamics (CFD) based numerical model. The breaking irregular wave forces on a monopile mounted on a slope are investigated with a numerical wave tank. The experimental and numerical irregular free surface elevations are compared in the frequency-domain for the different locations in the vicinity of the cylinder. A numerical analysis is performed for different wave steepness cases to understand the influence of wave steepness on the breaking irregular wave loads. The wave height transformation and energy level evolution during the wave shoaling and wave breaking processes is investigated. The higher-frequency components generated during the wave breaking process are observed to play a significant role in initiating the secondary force peaks. The free surface elevation skewness and spectral bandwidth during the wave transformation process are analysed and an investigation is performed to establish a correlation of these parameters with the breaking irregular wave forces. The role of the horizontal wave-induced water particle velocity at the free surface and free surface pressure in determining the breaking wave loads is highlighted. The higher-frequency components in the velocity and pressure spectrum are observed to be significant in influencing the secondary peaks in the breaking wave force spectrum. 相似文献
8.
《Ocean Engineering》1999,26(3):255-276
A Eulerian–Lagrangian method (ELM) is employed for the simulation of wave propagation in the present research. The wave action conservation equation, instead of the wave energy balance equation, is used. The wave action is conservative and the action flux remains constant along the wave rays. The ELM correctly accounts for this physical characteristic of wave propagation and integrates the wave action spectrum along the wave rays. Thus, the total derivative for wave action spectrum may be introduced into the numerical scheme and the complicated partial differential wave action balance equation is simplified into an ordinary differential equation. A number of test cases on wave propagation are carried out and show that the present method is stable, accurate and efficient. The results are compared with analytical solutions and/or other computed results. It is shown that the ELM is superior to the first-order upwind method in accuracy, stability and efficiency and may better reflect the complicated dynamics due to the complicated bathymetry features in shallow water areas. 相似文献
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全球海洋高频波动主振荡周期的纬向带状分布特征 总被引：2，自引：2，他引：0
基于1992年10月至2000年12月的TOPEX/Poseidon和ERS-1/2卫星高度计资料,分析了周期短于150d的高频波动及其能量的空间分布特征.在功率谱密度计算基础上,分析特定频段所含能量占周期短于150d的高濒波动总能量的百分比,发现该频段最强振荡(下文称主振荡)所对应的周期从近赤道的1个月逐步增加至南北纬30°附近的4个月,进一步分析表明主振荡周期的这种变化是连续的,与西向行星Rossby波的相速随纬度增加而变慢相对应.主振荡所对应的周期在全球海洋中呈显著的带状分布.进而表明在14°N(S)附近60d周期的振荡除通常所认为的由于潮汐混淆所造成的虚假信号之外,主要是行星Rossby波形态的真实信号. 相似文献
11.
多方向不规则波传播变形数值模拟 总被引：2，自引：1，他引：1
在推广的缓坡方程数学模型基础上建立了多方向不规则波数学模型,综合考虑了波浪折射、绕射、反射、底摩擦和风能输入等因素。基于线性波浪理论,将波浪方向谱在频率和方向上按等能量分割法离散后,分别计算各组成波的传播变形,再计算合成波要素。缓坡方程数学模型采用改进的ADI法求解,计算效率高,稳定性好。采用椭圆形浅滩不规则波模型试验结果和单突堤不规则波绕射理论解对数学模型进行了验证,数值模拟结果和试验值及理论解符合良好。利用该模型进行了某港港内波浪折射、绕射和反射的联合数值模拟,给出了合理的港内波高分布。 相似文献
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The effects of hurricane forward speed(V) and approach angle(θ) on storm surge are important and a systematic investigation covering possible and continuous ranges of these parameters has not been done before. Here we present such a study with a numerical experiment using the Finite Volume Community Ocean Model(FVCOM).The hurricane track is simplified as a straight line, such that V and θ fully define the motion of the hurricane. The maximum surge is contributed by both free waves and a forced storm surge wave moving with the hurricane.Among the free waves, Kelvin-type waves can only propagate in the down-coast direction. Simulations show that those waves can only have a significant positive storm surge when the hurricane velocity has a down-coast component. The optimal values of V and θ that maximize the storm surge in an idealized semi-circular ocean basin are functions of the bathymetry. For a constant bathymetry, the maximum surge occurs when the hurricane approaches the coast from the normal direction when the free wave generation is minimal; for a stepped bathymetry, the maximum surge occurs at a certain acute approach angle which maximizes the duration of persistent wind forcing; a step-like bathymetry with a sloped shelf is similar to the stepped bathymetry, with the added possibility of landfall resonance when the free and forced waves are moving at about the same velocity. For other cases, the storm surge is smaller, given other parameters(hurricane size, maximum wind speed, etc.)unchanged. 相似文献
13.
This work presents a new approach for simulating the random waves in viscous fluids and the associated bottom shear stresses. By generating the incident random waves in a numerical wave flume and solving the unsteady two-dimensional Navier-Stokes equations and the fully nonlinear free surface boundaiy conditions for the fluid flows in the flume, the viscous flows and laminar bottom shear stresses induced by random waves axe determined. The deterministic spectral amplitude method implemented by use of the fast Fourier transform algorithm was adopted to generate the incident random waves. The accuracy of the numerical scheme is confirmed by comparing the predicted wave spectrum with the target spectrum and by comparing the nanlerical transfer function between the shear stress and the surface elevation with the theoretical transfer function. The maximum bottom shear stress caused by random waves, computed by this wave model, is compared with that obtained by Myrhaug＇ s model （1995）. The transfer function method is also employed to determine the maximum shear stress, and is proved accurate. 相似文献
14.
An improved coupling of numerical and physical models for simulating 2D wave propagation is developed in this paper. In the proposed model, an unstructured finite element model (FEM) based Boussinesq equations is applied for the numerical wave simulation, and a 2D piston-type wavemaker is used for the physical wave generation. An innovative scheme combining fourth-order Lagrange interpolation and Runge-Kutta scheme is described for solving the coupling equation. A Transfer function modulation method is presented to minimize the errors induced from the hydrodynamic invalidity of the coupling model and/or the mechanical capability of the wavemaker in area where nonlinearities or dispersion predominate. The overall performance and applicability of the coupling model has been experimentally validated by accounting for both regular and irregular waves and varying bathymetry. Experimental results show that the proposed numerical scheme and transfer function modulation method are efficient for the data transfer from the numerical model to the physical model up to a deterministic level. 相似文献
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An improved coupling of numerical and physical models for simulating 2D wave propagation is developed in this paper. In the proposed model, an unstructured finite element model （FEM） based Boussinesq equations is applied for the numerical wave simulation, and a 2D piston-type wavemaker is used for the physical wave generation. An innovative scheme combining fourth-order Lagrange interpolation and Runge-Kutta scheme is described for solving the coupling equation. A Transfer function modulation method is presented to minimize the errors induced from the hydrodynamic invalidity of the coupling model and/or the mechanical capability of the wavemaker in area where nonlinearities or dispersion predominate. The overall performance and applicability of the coupling model has been experimentally validated by accounting for both regular and irregular waves and varying bathymetry. Experimental results show that the proposed numerical scheme and transfer function modulation method are efficient for the data transfer from the numerical model to the physical model up to a deterministic level. 相似文献
16.
It is difficult to compute far-field waves in a relative large area by using one wave generation model when a large calculation domain is needed because of large dimensions of the waterway and long distance of the required computing points. Variation of waterway bathymetry and nonlinearity in the far field cannot be included in a ship fixed process either. A coupled method combining a wave generation model and wave propagation model is then used in this paper to simulate the wash waves generated by the passing ship. A NURBS-based higher order panel method is adopted as the stationary wave generation model; a wave spectrum method and Boussinesq-type equation wave model are used as the wave propagation model for the constant water depth condition and variable water depth condition, respectively. The waves calculated by the NURBS-based higher order panel method in the near field are used as the input for the wave spectrum method and the Boussinesq-type equation wave model to obtain the far-field waves. With this approach it is possible to simulate the ship wash waves including the effects of water depth and waterway bathymetry. Parts of the calculated results are validated experimentally, and the agreement is demonstrated. The effects of ship wash waves on the moored ship are discussed by using a diffraction theory method. The results indicate that the prediction of the ship induced waves by coupling models is feasible. 相似文献
17.
Point absorber wave energy device with multiple degrees of freedom (DOF) is assumed to have a better absorption ability of mechanical energy from ocean waves. In this paper, a coaxial symmetric articulated point absorber wave energy converter with two degrees of freedom is presented. The mechanical equations of the oscillation buoy with power take-off mechanism (PTO) in regular waves are established. The three-dimensional numerical wave tank is built in consideration of the buoy motion based upon the CFD method. The appropriate simulation elements are selected for the buoy and wave parameters. The feasibility of the CFD method is verified through the contrast between the numerical simulation results of typical wave conditions and test results. In such case, the buoy with single DOF of heave, pitch and their coupling motion considering free (no PTO damping) and damped oscillations in regular waves are simulated by using the verified CFD method respectively. The hydrodynamic and wave energy conversion characteristics with typical wave conditions are analyzed. The numerical results show that the heave and pitch can affect each other in the buoy coupling motion, hydrodynamic loads, wave energy absorption and flow field. The total capture width ratio with two coupled DOF motion is higher than that with a single DOF motion. The wave energy conversion of a certain DOF motion may be higher than that of the single certain DOF motion even though the wave is at the resonance period. When the wave periods are high enough, the interaction between the coupled DOF motions can be neglected. 相似文献
18.
We consider a plane problem of barotropic seiches generated by a front of atmospheric pressure moving over a bounded basin.
A system of nonlinear equations of long waves is solved by the finite-difference method with regard for the bottom friction
and Earth's rotation. The numerical analyses are performed for two basins with distributions of depths typical of the Black
Sea. It is shown that the passage of a baric front over the basin leads to the generation of lower seiches. The oscillations
of level and the corresponding currents are especially intense in the shallow-water zones of the basins. The seiches become
more intense as the velocity of transfer of the atmospheric front increases and the width of the front decreases. Earth's
rotation leads to the generation of longshore currents and promotes the process of weakening of residual oscillations of the
fluid following the passage of the front. The influence of nonlinearity on seiches is small for the analyzed basins.
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Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 3–18, March–April, 2008. 相似文献
19.
We perform the numerical analysis of the influence of variations of the geometric characteristics of an annular basin of variable depth on the space structure of wave motions generated by the oscillations of atmospheric pressure periodic as functions of time. Within the framework of the linear theory of long waves, we determine (with regard for the action of the Coriolis force) the ranges of periods inside which the free surface of liquid has a fixed number of nodes. The dependence of these ranges on the parameters of the basin is established and the shapes of the free-surface profiles are compared for circular and axisymmetric waves.Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 14–23, September–October, 2004.This revised version was published online in May 2005 with corrections to cover date. 相似文献
20.
A numerical method, based on a boundary integral equation combined with a non-linear time stepping procedure for the free water surface, is developed for simulations of the interaction between highly non-linear water waves and submerged horizontal cylinders. The method is based on potential theory, and the omission of viscous effects restricts the wave-structure interaction computations to low Keulegan-Carpenter numbers where inertia forces are dominant. The numerical scheme is verified by computations with a steep wave of exact form during several wave periods, and by computations of a breaking wave. A new method for tracing the orbits of water particles in the fluid domain is developed, and the influence from submerged structures on the orbits is visualized through several computational examples. The wave forces on submerged structures are computed and are found to correspond well with other computed results for low Keulegan-Carpenter numbers. 相似文献