ISSN:0309-1929    

DOI:10.1080/03091928308221760

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The present description of the Trondheimsfjord is based on monthly hydrographical data collected between 1963-80, together with data from periods of intensive measurements using a great variety of methods. The estuarine circulation derives mainly from six big rivers that flow into the fjord. A simple hydraulic theory is used to calculate the residence time of the brackish layer. Tidal flows dominate the water exchange above the sill level as well as the turbulent vertical mixing and diffusion that eventually lead to replacement of the deep water in the basins. Current measurements at the sill reveal significant baroclinically driven residual currents. Variations in the vertical stratification outside the fjord are found to be important for the water exchange. A statistical treatment clearly shows that there is a need for long continuous hydrographic series running over decades in order to distinguish natural variations from the influence of human activity.

ISSN:0309-1929    

DOI:10.1080/03091928308221761

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The “mesolayer” theory of turbulence is applied to the problem of rotating boundary layers. The first sections concern smooth surfaces and develop the concept of a mesolayer which, in accordance with earlier work on other fluid systems by the author and collaborators, has a thickness of order (hH)½wherehis the inner length andHis the outer length. In the present problem,hisv/uτwhere v is the kinematic viscosity and uτ/fis the friction velocity andHis the Ekman-layer thicknessuτ/f. The new results seem to agree with laboratory experiments with rotating fluids.

ISSN:0309-1929    

DOI:10.1080/03091928308221762

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A rotating tow facility whose principle element is a long acrylic channel of rectangular cross-section has been developed. A smooth flexible belt, which can be translated along the channel axis, serves as a false horizontal floor. The system is mounted on a turntable which rotates at a constant angular speed about a vertical axis. The working fluid is bounded above by a sheet of acrylic plastic which can be tilted to simulate the beta effect. Topographic features are mounted on the belt and the flow past these obstacles is made visible by utilizing the electrolytic precipitation technique and recorded by a video tape camera system which translates with the belt.

ISSN:0309-1929    

DOI:10.1080/03091928308221763

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Previous studies of parametric instabilities of a finite-amplitude internal gravity wave in dissipationless Boussinesq fluids predict the largest growth rates for perturbations with vanishingly small wavelengths, leading to the practical question of which perturbations are most unstable in the presence of molecular dissipation. At high Reynolds numbers, the amplitude of the gravity wave decays on spatial and temporal scales which are large compared to the wavelength and period respectively. Therefore, the interaction equations describing the growth or decay of small perturbations can be solved by a conventional expansion procedure yielding a leading term in the form of a Floquet solution. Numerical calculations show that the competitive processes of parametric growth and viscous decay produce instabilities with maximum growth rates at wavelengths which may be similar or even longer than the wavelength of the basic gravity wave. Two transformations leading to a significant reduction of computational expenditure are discussed.

ISSN:0309-1929    

DOI:10.1080/03091928308221764

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

In connection with the large dish at the Arccibo Observatory (Puerto Rico), the mobile SOUSY VHF Radar has been used to carry out velocity measurements in the troposphere with height and time resolutions of a few hundreds of meters and some tens of seconds, respectively. During the passage of a strong subtropical jet stream, vertical velocity oscillations have been observed at heights of maximum wind shear. The height and time variations of the velocity and the background wind profile deduced from radiosonde data indicate that a Kelvin-Helmholtz instability (KHI), with a period of 340s, a wavelength of 12 km and a velocity amplitude of about 1 ms−1was the source of the oscillations. Model calculations show good agreement with the observed quantities.

ISSN:0309-1929    

DOI:10.1080/03091928308221765

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A wave theory based on the non-linear shallow water equations for a two-layer fluid is constructed. The initial value conditions for the equations are the same as for the sudden release of a buoyant fluid. The theory has been tested in a series of experiments of lock-exchange type. Good agreement was found between prediction and experimental data for large times.

ISSN:0309-1929    

DOI:10.1080/03091928308221766

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Optical techniques are described for the visualization and measurement of internal waves generated by a cylinder moving through a stably stratified fluid. Examples of the uses of colour schlieren and shearing interferometric methods respectively are given.

ISSN:0309-1929    

DOI:10.1080/03091928308221767

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor