共查询到20条相似文献，搜索用时 15 毫秒
1.
Junliang Gao Xiaojun Zhou Li Zhou Jun Zang Qiang Chen Haoyu Ding 《Ocean Dynamics》2018,68(12):1663-1681
Oscillations within an enclosed rectangular harbor and a set of partially opened rectangular harbors with various widths and locations of entrance induced by cubic water surface disturbances with different initial heights and locations are simulated using FUNWAVE 2.0 model. The height and the location of the cubic water surface disturbance refer to its thickness and its relative horizontal position inside the harbor, respectively. The water depth inside and outside all harbors is set to be constant. The aim of this paper is to investigate how different heights and locations of the water surface disturbance and various widths and locations of harbor entrance affect the oscillations inside the harbor. Results show that for the given harbors and the range of the initial height of water surface disturbance studied in this paper, all the response amplitudes of various eigenfrequencies increase linearly with the initial height of water surface disturbance. The variations of the initial location of water surface disturbance along the backwall and sidewall of the harbor can significantly change the transverse and longitudinal oscillation patterns of various modes, respectively. The effects of the variations of the width and location of the harbor entrance on the response amplitudes of various resonant modes both depend on the relative positions of their node lines and antinode lines to the harbor entrance. 相似文献
2.
The infragravity (IG) period oscillations inside an elongated rectangular harbor near the offshore fringing reef induced by normal-incident bichromatic short wave groups are simulated using a fully nonlinear Boussinesq model, FUNWAVE 2.0. Based on an IG wave separation procedure, this article presents a systematical investigation on how the maximum IG period component amplitude, the bound and free IG waves, and their relative components inside the harbor change with respect to the plane reef-face slope and the incident short wave amplitude under the condition of the 2nd to the 5th modes. For the given harbor and the ranges of the reef-face slope and the incident short wave amplitude studied in this paper, it is shown that both the maximum IG period component amplitude and the free IG wave component amplitude inside the harbor fluctuate widely with the reef-face slope, and their changing trends with the reef-face slope are almost identical with each other, while the bound IG waves inside the harbor seem insensitive to it. Both the maximum IG period component amplitude and those of the bound and free IG standing waves inside the harbor change cubically with the incident short wave amplitude. 相似文献
3.
Lee-Or Merkine 《地球物理与天体物理流体动力学》2013,107(1-2):25-37
Abstract The mutual interaction of fields induced by spatially separated potential vorticity sources in a quasi-geostrophic barotropic flow is investigated using the weakly nonlinear approach. It is found that a powerful nonlinear response can be triggered by Rossby lee waves. This resonance phenomenon which dominates all other nonlinear corrections depends on certain global resonance conditions and on the change in the phase of the Rossby lee wave across the distance separating the sources. The response is particularly strong for topographic forcing possessing δ-function characterisitics. 相似文献
4.
Andrew J. Willmott 《地球物理与天体物理流体动力学》2013,107(1-4):39-63
Abstract This paper investigates the generation of linear baroclinic Rossby waves by meridional oscillations of a climatological zonal wind stress in a reduced gravity ocean bounded by an eastern coastline. Using a power series technique an analytical solution is derived for the interfacial displacement. It is found that for a given period of oscillation of the zonal winds, a finite number of propagating Rossby waves will be generated with frequencies equal to a harmonic of the forcing frequency. The number of propagating modes increases with increasing period of the wind stress. In addition to the propagating waves the complete solution for the interfacial displacement consists of a rapidly convergent infinite sum of evanescent terms. The displacement field is calculated for atmospheric forcing parameters typical of those found at mid-latitudes. Further, it is shown that a near resonant response can be generated using atmospheric parameter values typical of those found over the North Pacific. 相似文献
5.
Cai Shuqun Wu Yuqi Xu Jiexin Chen Zhiwu Xie Jieshuo He Yinghui 《中国科学:地球科学(英文版)》2021,64(10):1674-1686
Numerous internal solitary waves(ISWs) have been observed in the southern Andaman Sea. In this study, the two-dimensional Massachusetts Institute of Technology general circulation model is applied to investigate the dynamics of ISWs and explore the effects of the bottom topography and tidal forcing on the generation and propagation of ISWs in the southern Andaman Sea. The results show that the large-amplitude depression ISWs are mainly generated via the oscillating tidal flow over the sill of the Great Channel, and the generation of ISWs is subject to the lee wave regime. The Dreadnought Bank cannot generate ISWs itself; however, it can enhance the amplitudes of eastward-propagating ISWs generated from sill A, owing to constructive interference of internal tide generation between the sill of the Great Channel and the Dreadnought Bank. The eastward-propagating ISWs generated by the eastern shallow sill near the continental shelf can propagate to the shelf, where they evolve into elevation waves because of the shallow water. Sensitivity runs show that both the semidiurnal and diurnal tides over the sill of the Great Channel can generate ISWs in this area. However, the ISWs generated by diurnal tides are much weaker than those generated by semidiurnal tides. Mixed tidal forcing has no significant effect on the generation of ISWs. 相似文献
6.
Dennis Moore 《地球物理与天体物理流体动力学》2013,107(1-2):237-247
Abstract Second order effects due to the presence of a first order free oscillation at a single frequency in a variable depth rotating ocean are examined. It is found that the second order Lagrangian mean velocity (mass transport velocity) satisfies the linearized equations for unforced steady geostrophic motion. This implies that if the ocean basin is laterally bounded and contains no closed geostrophic contours, the second order Lagrangian mean velocity vanishes everywhere. 相似文献
7.
The role of mud erosion under waves in governing cohesive sediment transport in estuarial and coastal waters is well known. A laboratory study was conducted in order to elucidate the mechanism by which soft muds erode under progressive waves in a flume. Two types of cohesive sediment were used, a commercial kaolinite and an estuarial mud. Beds were formed by pouring in a pre-prepared sediment-water slurry and allowing the deposit to consolidate for a period ranging from 2 to 14 days. A multi-layered hydrodynamic model, which considers the mud to be viscoelastic, has been developed and used to evaluate the bed shear stress at the oscillating mud-water interface. The viscoelastic property of the mud has been confirmed by rheological measurements, and model results on velocity, pressure and wave attenuation verified against flume data. Concentration profiles indicate a distinct evolutionary pattern resulting in a highly stratified suspension. Just above the bed, a thin layer of fluid mud is generated. Above this layer, the suspension concentration is significantly lower. This two-layered feature of the concentration profile is related to the oscillatory response of the mud and water layers, and the associated momentum exchange and mass diffusion characteristics. An expression relating the rate of erosion to the bed shear stress in excess of bed shear resistance has been developed. Generation of fluid mud during erosion is a significant feature of the role of waves over mud. 相似文献
8.
Spatial variation of earthquake ground motion is an important phenomenon that cannot be ignored in the design and safety of strategic structures. Several models have been developed to describe this variation using statistical, mathematical or physical approaches. The latter approach is not specific to an event. A recent contribution, which uses such an approach and called complete stochastic deamplification approach (CSDA), was developed [1]. The aim of this paper is to analyze the spatial variation of earthquake motion induced by the propagation of body waves using the CSDA. Coherency functions are evaluated for the cases of SH–SV–P waves propagating through stratified soil. Results obtained show that the variation of the coherency function is not the same for vertical and horizontal components and that the motion is more coherent at depth than at the free surface. In fact, we found that the rate of decrease with frequency and distance is not the same if P–SV waves propagate through stratified soil. 相似文献
9.
Ｉｎｆｌｕｅｎｃｅｏｆｌｏｎｇｐｅｒｉｏｄｓｅｉｓｍｉｃｗａｖｅｓｉｎ┐ｄｕｃｅｄｂｙｔｈｅＴａｉｗａｎｌａｒｇｅｅａｒｔｈｑｕａｋｅｏｎＳｈａｎｇｈａｉａｒｅａＫＵＮ－ＹＵＡＮＺＨＵＡＮＧ（庄昆元）ＹＯＮＧ－ＬＩＮＸＵ（徐永林）ＪＩＡＮ－ＷＥＮＳ... 相似文献
10.
Yosuke Igeta Tatsuro WatanabeHaruya Yamada Katsumi TakayamaOsamu Katoh 《Continental Shelf Research》2011,31(16):1739-1749
Current observations were made from 14 July 2006 to 31 March 2007, using an acoustic Doppler current profiler mounted on the seafloor near the eastern coast of the Noto Peninsula, Japan, to investigate strong coastal currents induced by large-amplitude coastal-trapped waves (CTWs) and near-inertial fluctuations (NIFs). The CTWs were generated by the winter monsoon and the passage of a typhoon during the observation period. Two types of strong currents with velocities higher than 50 cm s-1 were observed. One type, the strong current in winter (SCW), had the coast on the left to its direction of flow. This current was observed after a strengthening of the winter monsoon in January 2007. The other type, the strong current in fall (SCF), had the coast on the right to its direction of flow and was observed after the passage of a typhoon in September 2006. The SCW was inferred to be formed mainly by low-mode CTWs without NIFs. Compared to the SCW, the SCF had a more complicated vertical structure and time variations. The SCF was inferred to be generated by low-mode CTWs strengthened by NIFs. The contributions of NIFs to the strong coastal currents became important when the wind stress direction was rotating clockwise. 相似文献
11.
Zhihua Xie 《Ocean Dynamics》2017,67(10):1251-1261
Wind effects on periodic breaking waves in the surf zone have been investigated in this study using a two-phase flow model. The model solves the Reynolds-averaged Navier–Stokes equations with the k ? ?? turbulence model simultaneously for the flows both in the air and water. Both spilling and plunging breakers over a 1:35 sloping beach have been studied under the influence of wind, with a focus during wave breaking. Detailed information of the distribution of wave amplitudes and mean water level, wave-height-to-water-depth ratio, the water surface profiles, velocity, vorticity, and turbulence fields have been presented and discussed. The inclusion of wind alters the air flow structure above water waves, increases the generation of vorticity, and affects the wave shoaling, breaking, overturning, and splash-up processes. Wind increases the water particle velocities and causes water waves to break earlier and seaward, which agrees with the previous experiment. 相似文献
12.
Ice collapsing into the waters of proglacial Briksdal Lake, western Norway, generates waves which rework shoreline sediments. Swash establishes graded gravel ridges sub-perpendicular to the shoreline, derived from material eroded by backwash. A terminal gravel bar at the lakeward limit of wave-induced transport marks the maximum depth of water surface waves. 相似文献
13.
The oceanic mixed layer (OML) response to an idealized hurricane with different propagation speeds is investigated using a
two-layer reduced gravity ocean model. First, the model performances are examined with respect to available observations relative
to Hurricane Frances (2004). Then, 11 idealized simulations are performed with a Holland (Mon Weather Rev 108(8):1212–1218,
1980) symmetric wind profile as surface forcing with storm propagation speeds ranging from 2 to 12 m s−1. By varying this parameter, the phasing between atmospheric and oceanic scales is modified. Consequently, it leads to different
momentum exchanges between the hurricane and the OML and to various oceanic responses. The present study determines how OML
momentum and heat budgets depend on this parameter. The kinetic energy flux due to surface wind stress is found to strongly
depend on the propagation speed and on the cross-track distance from the hurricane center. A resonant regime between surface
winds and near-inertial currents is clearly identified. This regime maximizes locally the energy flux into the OML. For fast-moving
hurricanes (>6 m s−1), the ratio of kinetic energy converted into turbulence depends only on the wind stress energy input. For slow-moving hurricanes
(<6 m s−1), the upwelling induced by current divergence enhances this conversion by shallowing the OML depth. Regarding the thermodynamic
response, two regimes are identified with respect to the propagation speed. For slow-moving hurricanes, the upwelling combined
with a sharp temperature gradient at the OML base formed in the leading part of the storm maximizes the oceanic heat loss.
For fast propagation speeds, the resonance mechanism sets up the cold wake on the right side of the hurricane track. These
results suggest that the propagation speed is a parameter as important as the surface wind speed to accurately describe the
oceanic response to a moving hurricane. 相似文献
14.
许多实际的地震中已经观测到地表地形对地表地震动产生影响(地形效应),这种影响背后的成因、影响因素、影响规律至今还不太清楚,因此地震学中、地震工程学中都围绕这一课题展开了相应的研究.本文以地震波模拟为手段,以点力源激发下的SH横波地震波传播为对象,研究地形形态、震源的物理特征对SH波地表地震动的影响,研究内容主要包括:地形陡度和地形复杂度对地形效应的作用;震源所处位置、震源频率与地形效应的关系,揭示出地形效应的成因受局部地表张角的控制,张角越小地形的放大作用越强. 相似文献
15.
本文以波函数展开法为基础,给出了SV波与P波入射时大型引水隧道平面地震响应的解析解.并根据解析解,利用数值方法对建立的场地模型进行了计算分析,研究了隧道结构-水体体系的地震响应.重点讨论了入射波频率、入射角、衬砌力学性能对衬砌结构动力响应的影响.分析表明,大型引水隧道动力响应受入射波频率和入射角的影响较为明显,而衬砌力... 相似文献
16.
Sediment movement in the wave boundary layer above a mobile sediment bed is complex.A velocity formula for the boundary layer is proposed for sheet flow induced by asymmetric waves above a mobile sediment bed.The formula consists of a free stream velocity and a defect function which contains a phase-lead,boundary layer thickness and mobile sediment bed.Phase-lag of sediment movement is considered in the formula for the mobile sediment bed.The formula needs six dependent variables about asymmetric wave and sediment characteristics.Asymmetry effects on parameters(orbital amplitude,roughness height,bed shear stress,and boundary layer thickness)are properly considered such that the formula can yield velocity differences among onshore,offshore,acceleration,and deceleration stages.The formula estimates the net boundary layer velocity resulting from the mobile sediment bed and asymmetric boundary layer thickness.In addition,a non-constant phase-lead also contributes to the net boundary layer velocity in asymmetric oscillatory sheet flow.Results of the formula are as good as that of a two-phase numerical model.Sheet flow transport induced by asymmetric waves,and the offshore net sediment transport rate with a large phase-lag under velocity-skewed waves,can be adequately estimated by the formula with a power sediment concentration function. 相似文献
17.
This paper presents the effects of soil layering on the characteristics of basin-edge induced surface waves and associated
strain and aggravation factor. The simulated results revealed surface wave generation near the basin-edge. The first mode
of induced Love wave was obtained in models having increasing velocity with depth and a large impedance contrast between the
soil layers. Amplitude amplification or de-amplification of body waves was proportional to the impedance contrast between
the soil layers. The average aggravation factor was inversely proportional to the impedance contrast between the soil layers
in case of increasingvelocity models and proportional in case of decreasing-velocity basinedge models. On the other hand,
the maximum strain was inversely proportional to the impedance contrast between the soil layers in both cases. On the average,
strain was greater in case of increasing-velocity models but the average aggravation factor was greater in case of decreasingvelocity
models. 相似文献
18.
A theoretical model for reverse water-level fluctuations induced by transient permeability in thrust fault zones 总被引：1，自引：0，他引：1
A numerical model was applied to simulate the poroelastic response to changes in fault permeability as a result of earthquakes. The ‘fault valve’ model describes faults as impermeable barriers for fluids except immediately after earthquakes, when fault zones are damaged and transient pathways for fluids are created. In this case the fault is viewed as a discharging well, draining fluids from the surrounding rock. The reverse water-level effect is characterized by the increase of water level in adjacent aquifers and aquitards, resulting from withdrawing fluids through a well. Theoretical calculations suggest that the reverse water-level effect exists also in earthquake cycling and is in the same order of magnitude as the co-seismic hydraulic head change. A significant rise of the hydraulic head (>1 m) occurs within the country rock from both sides of the fault. The rise of the water level takes months to years to occur, and perhaps that is why it cannot be easily distinguished from seasonal hydrologic changes observed in the field. The reverse water-level effect also propagates away from the fault at a rate of hundreds of meters per year, depending on the permeability of the country rock. In deep formations where the permeability is low, the propagation takes years. The magnitude of the reverse water-level effect is greater when the fault efficiently drains fluids, when it is highly permeable and slow to reseal. 相似文献
19.
Scattering of SH waves induced by a symmetrical V-shaped canyon: a unified analytical solution 总被引：1，自引：1，他引：1
This paper reports a series solution of wave functions for two-dimensional scattering and diffraction of plane SH waves induced by a symmetrical V-shaped canyon with different shape ratios. A half-space with a symmetrical V-shaped canyon is divided into two sub-regions by using a circular-arc auxiliary boundary. The two sub-regions are represented by global and local cylindrical coordinate systems, respectively. In each coordinate system, the wave field satisfying the Helmholtz equation is represented by the separation of variables method, in terms of the series of both Bessel functions and Hankel functions with unknown complex coefficients. Then, the two wave fields are described in the local coordinate system using the Graf addition theorem. Finally, the unknown coefficients are sought by satisfying the continuity conditions of the auxiliary boundary. To consider the phase characteristics of the wave scattering, a parametric analysis is carried out in the time domain by assuming an incident signal of the Ricker type. Surface and subsurface transient responses demonstrate the characteristics and mechanisms of wave propagating and scattering. 相似文献
20.
Three-dimensional deformation and strain induced by municipal pumping, Part 2: Numerical analysis 总被引：3，自引：0，他引：3
Field measurements consisting of water levels from a municipal well and three-dimensional surface deformations and strains from high-precision GPS measurements at various radial distances from the well were collected as part of a 62-day controlled aquifer test at Mesquite, NV. These measurements were used as observations in several numerical models and a parameter estimation code to characterize and constrain hydraulic and mechanical properties of a 400 m thick basin-fill aquifer. A parsimonious approach was used in conceptualizing the aquifer system. Nonetheless, results from the calibrated deformation and flow models accurately reproduced the observed head and deformations during the first 20 days of pumping, the time at which a new equilibrium was achieved. Surface deformations were shown to reflect hydraulic anisotropy and direction of principal conductivity. In addition, the radius of influence and cone of depression from pumping was approximated in spite of the fact that no monitoring well data existed at the site. Sensitivity analysis indicates that cyclical head values are most sensitive to changes in horizontal hydraulic conductivity, while time-dependent vertical deformations are most sensitive to changes in skeletal specific storage. This investigation shows that GPS monitoring can be used in place of costly monitoring wells to characterize aquifers for water-management purposes where skeletal deformation tends to be elastic. 相似文献
