ISSN:0022-1686    

DOI:10.1080/00221689009499068

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The velocity field beneath a series of progressive gravity waves was investigated using laser Doppler anemometry. The drift velocity was observed to vary with respect to both time (t) and distance (x) along the wave flume. Vorticity profiles, calculated from the velocity data, suggest that this development has its origins within the near shore region. In most cases a stable configuration is eventually achieved. A negative shear current is established in which the back flow is between 3 and 4 times larger than the predicted irrotational motion. Even in those regions which are directly adjacent to the viscous boundary layers the motion appears to depend upon the horizontal convection of vorticity, rather than its vertical diffusion. Indeed, there is a clear transition between the dominant mode of vorticity transportation. The final solution is characterised by negative near bed velocities and positive vorticity within the near surface region. This is completely opposite to that predicted by a diffusion solution, and indicates the importance of convection from the near shore region.

ISSN:0022-1686    

DOI:10.1080/00221689009499069

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A closed-form, linear analytic solution for the problem of wave interaction with a hinged flexible breakwater is presented. The fluid motion is described theoretically by utilizing an eigenseries representation of linear wave theory. The flexible breakwater is modelled by a beam hinged at sea bottom and with moorings at top. The beam is assumed to have uniform stiffness and mass distribution. The coupling problem of fluid and structure interaction is solved in differential forms. From the present theoretical solution, the effects of the structural flexibilities on the reflecting, transmitting waves, and the structural responses to the incident waves are investigated. Present analytic solutions compare favorably well with experimental results.

ISSN:0022-1686    

DOI:10.1080/00221689009499070

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Significant wave heights and wave periods obtained from field measurements in Lake Balaton, Hungary, were compared with two versions of the shallow water wave hindcasting model published by the U.S. Army Corps of Engineers. The version presented in CERC [3, 4] was found to give very good hindcasts of wave height but fall -20% low on wave period. The model presented in CERC [5] was 15-20% above the earlier version at long fetches and approximately equivalent at shorter fetches.

ISSN:0022-1686    

DOI:10.1080/00221689009499071

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Analytical solutions for the asymptotic behaviour of two-dimensional flow with dead zones have been obtained using the Aris method of moments. These spatial and temporal solutions demonstrate the relative contributions of main flow shear dispersion and dead zone trapping to the total rate of longitudinal dispersion. A general solution for spatial distributions was recently given in the literature but was not applied to a specific dead zone geometry. Good agreement is found with the dead zone experiments of Valentine [30] and previous numerical solutions. Steady-state equilibrium profile solutions for the variations in mass, centroid and variance over the flow cross-section au derived for both spatial and temporal distributions. While the centroid, variance and skew all increase linearly during the equilibrium period, the kurtosis increase quadratically, consistent with an eventual asymptote of the kurtosis coefficient to the Gaussian value of 3.0.

ISSN:0022-1686    

DOI:10.1080/00221689009499072

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Shock formation may present problems in the course of kinematic cascade modelling. With regard to the choice of an adequate algorithm of solution it is therefore important to know beforehand, if discontinuities are to be expected or not. A generalized criterion including cases of time-dependent rates of rainfall excess is derived. For constant lateral inflow it can be shown to correspond to the previously derived Kibler- Woolhiser criterion.

ISSN:0022-1686    

DOI:10.1080/00221689009499073

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper investigates the scourhole developed by a plane jet entering shallow tailwater conditions. Through dimensional considerations and physical reasoning, the appropriate functional groups are identified. Experimental laboratory results are then used to evaluate the functional relationships and show that in shallow conditions, the jet can produce three very different scourhole regimes. Two are propagated where the jet permanently attaches itself to either the bed or the free surface boundary whilst the third is produced when the jet periodically flicks between the free and solid bed boundaries. Results are presented to illustrate the different hydraulic processes which are active during this unusual scourhole development.

ISSN:0022-1686    

DOI:10.1080/00221689009499074

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A numerical model is used to determine changes in the bed morphology resulting from the bed load and suspended transport of sand. The ability of the model to predict mean and turbulent quantities and the suspended transport of sand is assessed by appeal to laboratory flume experiments and field observations. The model is then applied to investigate changes that may be expected to occur in an initial bedform corresponding to asymmetrical sandwaves characteristic of those found in the coastal and estuarine environment. It is found that suspended transport may frequently dominate over bed load transport in producing changes in the bedform structure. The predicted evolution of the bedform is reasonably consistent with observations made of sediment fluxes and sandwave migration in the Taw Estuary, England.

ISSN:0022-1686    

DOI:10.1080/00221689009499075

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The standard ocean diffuser consists of a pipe on the ocean ff oor with ports alternately on either side. In New Zealand these ports are often sufficiently spaced such that port interference is small and thus a study of the flow from a single port in a stationary and a moving ambient fluid is relevant. A number of flow regimes occur where the discharge from the single port and the ambient are in opposite directions (a counterflow). This paper presents the results of an extensive experimental study of the possible flow patterns from these outfall ports.

ISSN:0022-1686    

DOI:10.1080/00221689009499076

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221689009499077

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor