共查询到20条相似文献，搜索用时 31 毫秒
1.
2.
The process of development of nonlinear oscillations of the free surface of a fluid caused by the action of a periodic mass
force in a bounded basin is numerically studied within the framework of the theory of long waves. The action of dissipative
forces is taken into account. The effect of nonlinearity and geometric characteristics of the basin on the parameters of the
generated wave field is analyzed.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 3–12, September–October, 2005. 相似文献
3.
Nonlinear axisymmetric oscillations of a warm baroclinic eddy are considered within the framework of an reduced-gravity model of the dynamics of a multilayer ocean. A class of exact analytical solutions describing pure inertial oscillations of an eddy formation is found. The thicknesses of layers in the eddy vary according to a quadratic law, and the horizontal projections of the velocity in the layers depend linearly on the radial coordinate. Owing to a complicated structure of the eddy, weak limitations on the vertical distribution of density, and an explicit form of the solution, the latter can be treated as a generalization of the exact analytical solutions of this form that were previously obtained for homogeneous and baroclinic eddies in the ocean. 相似文献
4.
C.Z. Wang 《Ocean Engineering》2005,32(2):107-133
A two-dimensional nonlinear random sloshing problem is analyzed by the fully nonlinear wave velocity potential theory based on the finite element method. A rectangular container filled with liquid subjected to specified horizontal random oscillations is studied. Both wave elevation and hydrodynamic force are obtained. The spectra of random waves and forces have also been investigated, and the effects of the peak frequencies and spectral width of the specified spectrum used for the generation of the random oscillations are discussed. It is found that the energy mainly concentrates at the natural frequencies of the container and is dominant at the ith order natural frequency when the peak frequency is close to the ith order natural frequency. Some results are compared between the fully nonlinear solutions, the linear solutions and the linear plus second-order solutions. 相似文献
5.
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.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 3–18, March–April, 2008. 相似文献
6.
Inertial oscillations as deep ocean response to hurricanes 总被引：1，自引：0，他引：1
We discuss the deep ocean response to passing hurricanes (aka typhoons), which are considered as generators of near-inertial, internal waves. The analysis of data collected in the northwestern
parts of the Pacific and Atlantic oceans in the hurricane season permit us to assess the deep ocean response to such a strong
atmospheric forcing. A large number of moorings (more than 100) in the northwestern Pacific have allowed us to characterize
the spatial features of the oceanic response to typhoons and the variable downward velocity of near-inertial wave propagation.
The velocity of their downward propagation varies in the range 1–10 m/hour. It is higher in the regions of low stratification
and high anticyclonic vorticity. The inertial oscillations generated by a hurricane last for 10–12 days. The mean anticyclonic
vorticity in the region increases the effective frequency of inertial oscillations by 0.001–0.004 cyc/hour. 相似文献
7.
A plane problem of free stationary gravitational waves in a horizontal current with vertical shear of the velocity is studied
in the linear statement. The determination of the parameters of waves is reduced to the solution of the Sturm–Liouville boundary-value
problem. For some vertical distributions of current velocity, we obtain analytic solutions. We propose a numerical algorithm
for finding the parameters of waves. On the basis of the performed analysis, we establish the possibility of existence of
stationary surface waves in currents for certain ranges of the Froude number. As the Froude number decreases, the waves become
shorter, which leads to a faster attenuation of waves disturbances with depth. Under the actual conditions, the waves are
short and suffer the influence of shear currents only in the subsurface layer of the ocean. 相似文献
8.
We consider a plane problem of generation of barotropic seiches in the case of motion of a region of disturbances of atmospheric
pressure over a bounded basin. The nonlinear system of equations of long waves with regard for the quadratic dependence of
bottom friction is solved by the finite-difference method. The calculations are carried out for three basins of variable depth
corresponding to rectangular sections of the Black Sea and Sea of Azov. It is shown that the passage of the baric anomaly
over the basin is accompanied by the generation of the lowest seiches. The oscillations of fluid are especially intense in
the shallow-water zones of the basins. Seiches exhibit a trend to intensification as the velocity of motion of the atmospheric
disturbance increases. The dependence on the width of the baric anomaly is not monotonic. In the shelf zone, the amplitude
of oscillations of the level can be several times higher that the pure hydrostatic response of the sea surface. In the analyzed
basins, the influence of nonlinearity on the seiches is weak.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 3–15, November–December, 2007. 相似文献
9.
Effect of ice cover on oscillations of fluid in a closed basin 总被引：1，自引：0，他引：1
I. V. Sturova 《Izvestiya Atmospheric and Oceanic Physics》2007,43(1):112-118
Within the framework of the linear theory of long waves, the problem of the effect of ice cover on seiche oscillations of fluid in a two-dimensional constant-depth basin is solved. The eigenfrequencies and eigenfunctions of seiche oscillations are obtained for different boundary conditions at ice edges: rigid coupling and free edges. The forced oscillations of fluid and ice under the action of a moving disturbance of atmospheric pressure are investigated. The change in the stress of ice bending is considered and it is shown that the coast ice can be broken. 相似文献
10.
T. Ya. Shul’ga 《Physical Oceanography》2006,16(6):313-321
By using the method of mathematical simulation, we study surge oscillations caused by the action of tangential wind stresses
in a bounded basin whose geometric parameters correspond to Lake Donuzlav. The dependences of the amplitudes of surges on
the magnitude and direction of the wind velocity are analyzed at several points of the coast.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 6, pp. 3–12, November–December, 2006. 相似文献
11.
J.A. Pinkster 《Ocean Engineering》1979,6(6):593-615
A recently developed method, based on three-dimensional potential theory, to compute the mean wave drifting forces on a free floating structure in regular waves, is extended to include low frequency oscillatory components which arise when the structure is floating in regular wave groups consisting of two regular waves with small difference frequency. This completes the information necessary for the determination of the wave drifting forces under arbitrary irregular wave conditions.In regular wave groups the drifting forces not only depend on the first order velocity potential and the first body motions, but also on the wave exciting forces due to the low frequency part of the second order potential. For the general three-dimensional case the latter contribution can only be determined numerically and at the expense of long computation times. Since this contribution is generally not large compared to components which may be determined using linear potential theory it is included using a simple approximation. Results of the method of approximation are compared with some two-dimensional cases for which exact solutions are known.Results of computations of the total mean and low frequency surge forces on a rectangular barge and a column stabilized semi-submersible platform are presented. For both structures, the computed mean surge drifting forces in regular head waves are compared with results of model tests.The computed components of the total mean drifting forces are presented. It appears that for both the barge and the semi-submersible the same components are of importance.For the semi-submersible, the computed low frequency second order surge forces in head waves are compared with results obtained from a test in irregular head waves using cross-bispectral analysis methods. 相似文献
12.
An analytical solution for the coupling problem of a two-dimensional tension leg structure interacting with a monochromatic linear wave train in an inviscid and incompressible fluid is presented. The tension legs are considered to be linearly elastic. The flow is further assumed to be irrotational and single-valued velocity potentials can then be defined.The boundary value problem is incorporated into a scattering and a radiation problem. The boundary value problems are then solved separately and combined to resolve all unknowns. The complete solutions of the velocity potentials are represented by the series of eigen-functions, and the surge motion of the structure is described in terms of the incident wave properties.The analytical solution is compared with a computer-coded numerical solution utilizing the boundary element method. The solutions agree very well, and both predict a resonant frequency for a specific structure which is different from the natural frequency of the structure due to the presence of the evanescent waves caused by the structure. 相似文献
13.
Stratified fluid flows caused by torsional or linear harmonic oscillations of a ring along the surface of an infinite vertical cylinder have been calculated by methods of the perturbation theory. The complete solutions of the linearized system of equations with sticking boundary conditions for velocity and impermeable boundary conditions for substance have been obtained taking into account viscosity and diffusion. Disturbances forming a conical beam of three-dimensional internal waves and families of small-scale components are identified. Formulas for calculating waves in media with different Schmidt numbers are described. 相似文献
14.
We consider a plane problem of generation of surface and internal waves in a bounded rotating basin of variable depth by a
front of atmospheric pressure moving over the basin. The fluid is assumed to be two-layer. The system of nonlinear long-wave
equations is solved numerically by the method of finite differences for the distribution of depths corresponding to a zonal
section of the Black-Sea basin. It is shown that the baric front moving over the basin generates barotropic and baroclinic
oscillations of the fluid. The intensity of disturbances depends on the velocity of motion and the width of the front. There
exists a velocity of motion of the front for which internal waves are generated especially efficiently. When the front leaves
the basin, we observe the formation of a packet of internal waves propagating from one lateral boundary of the basin to the
other boundary with reflections from the boundaries. 相似文献
15.
E. M. Dobryshman V. G. Kochina T. A. Letunova 《Izvestiya Atmospheric and Oceanic Physics》2013,49(5):494-503
Vortex simulation and the computation of fields of dynamic parameters of vortex structures (velocity, rotor velocity, and helicity) are carried out with the use of exact hydrodynamic equations in a cylindrical coordinate system. Components of centripetal and Coriolis accelerations are taken into account in the initial equations. Internal and external solutions are defined. Internal solutions ignore the disturbances of the pressure field, but they are considered in external solutions. The simulation is carried out so that the effect of accounting for spatial coordinates on the structure of the above fields is pronounced. It is shown that the initial kinetic energy of rotating motion transforms into the kinetic energy of radial and vertical velocity components in models with centripetal acceleration. In models with Coriolis acceleration, the Rossby effect is clearly pronounced. The method of an “inverse problem” is used for finding external solutions, i.e., reconstruction of the pressure field at specified velocity components. Computations have shown that tangential components mainly contribute to the velocity and helicity vortex moduli at the initial stage. 相似文献
16.
在流体力学中,描述流体运动有Lagrange方法和Euler方法.Euler方法是通过观测通过空间各固定位置点处流体质点的运动行为来描述流体运动规律,而Lagrange方法是跟踪各个流体质点,通过观测它们在时空运动中所走过的路径来描述流体的运动规律.在数学处理上,Euler方法较Lagrange方法简单,但Lagrange方法可以完全描述流体运动的整个流场的所有特性,而Euler方法却无法描述每个流体质点的运动轨迹.本文,我们研究具有刚性边界的三层流体系统中的界面内波,其中上层流体的密度比下层流体的密度大.通过在界面处引入朗格朗日匹配条件并使用微扰法得到了拉格朗日描述下的界面内波的一阶解、二阶解及三阶解,给出了质量输运速度、波频率、平均水平和质点运动轨迹的解.结果表明对于质量输运速度、波频率、平均水平和质点运动轨迹在界面处会有不连续性,但是我们发现在满足一定的三层流体水深比和密度比条件时这种不连续性将会消失. 相似文献
17.
Hirofumi Hinata Satoshi Fujii Keita Furukawa Tomoya Kataoka Masafumi Miyata Takashi Kobayashi Masahiro Mizutani Takahiro Kokai Nobuyoshi Kanatsu 《Estuarine, Coastal and Shelf Science》2011
Signals from the tsunami waves induced by the March 11, 2011 moment magnitude (Mw) 9.0 Tohoku-Oki earthquake and from subsequent resonances were detected as radial velocity variability by a high-frequency ocean surface radar (HF radar) installed on the eastern coast of the Kii Channel, at a range of about 1000 km from the epicenter along the eastern to southern coasts of Honshu Island. A time–distance diagram of band-passed (9–200 min) radial velocity along the beam reveals that the tsunami waves propagated from the continental shelf slope to the inner channel as progressive waves for the first three waves, and then natural oscillations were excited by the waves; and that the direction of the tsunami wave propagation and the axis of the natural oscillations differed from that of the radar beam. In addition, spectral analyses of the radial velocities and sea surface heights obtained in the channel and on the continental shelf slope suggest complex natural oscillation modes excited by the tsunami waves. 相似文献
18.
We study trapped baroclinic topographic waves in the northwest shelf of the Black Sea for the actual slopes of the bottom
and stratification. The time scales of trapped waves are determined. The space scales of the amplitude of oscillations are
computed. It is shown that the vertical distribution of the amplitude of oscillations is in qualitative agreement with the
experimentally observed distribution. The energy of topographic waves trapped by the sloping bottom is concentrated in the
bottom layer, which agrees with the data of measurements.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 5, pp. 44–52, September–October, 2006. 相似文献
19.
Anthony N. Williams 《Ocean Engineering》1985,12(1):25-43
The scattering of waves by both floating and submerged stationary elliptical breakwaters is investigated by means of linearised shallow water wave theory. This formulation leads to solutions for the fluid velocity potential in terms of Mathieu functions of real argument. Expressions are derived for the wave-induced forces and moments on the structures and their total and differential scattering cross-sections. Numerical results are presented for a range of wave and structural parameters.The present analysis serves as a prelude to a more comprehensive study of the problem without the shallow water restriction. 相似文献
20.
An analytic solution based on the division of the fluid domain is developed for the interaction of obliquely incident waves with infinite number of perforated caissons. The whole fluid domain is firstly divided into infinite sub-domains according to the division of structures, and subsequently eigenfunction expansion is employed to represent the velocity potential in each domain. A phase relation is utilized for the analysis of wave oscillation in each caisson, and the character of structure geometry is considered in setting up the mathematical model of reflection waves. The reflection waves from the present analysis include many propagation waves traveling in different directions when the incident wave frequency is high. Benchmark examinations show that the continuous condition of water particle velocity is satisfied at the front walls of caissons, and the reflection coefficients keep agreement with the energy conservation relation very well when porous effect parameter is infinite. Numerical results show that the reflection coefficients of obliquely incident waves are smaller when the length of caissons is shorter at low frequency. The wave reflection coefficients and the wave forces normal to caissons decrease and the wave forces along caissons increase with the increase of the wave incident angle. 相似文献