摘要:

A numerical investigation is made of flow and heat transfer characteristics of baroclinic waves using a new rotating cylindrical annulus, referred to as the Miller-Fowlis (MF) model. Special features of this annulus are: (1) the aspect ratio (height to width) is small, (2) the thermal gradients are imposed on the horizontal boundaries. In an effort to expand upon the previous experimental measurements, comprehensive numerical data are acquired for the finite-amplitude wave-present flow regime. Full three-dimensional Navier-Stokes equations are solved by utilizing a well established pseudospectral numerical technique. Three specific case studies are performed by using the parameter values which are selected by consulting the experimentally-obtained regime diagrams. The three-dimensional computations successfully captured the existence of finite-amplitude waves. Salient features of three-dimensional flow and thermal fields are presented. Both the zonal mean and deviatoric fields of essential flow variables are displayed and pertinent physical interpretations are attempted. Comprehensive examinations of flow properties and energetics are undertaken; post processing analyses and discussions are rendered. In the present MF model, the sidewall layers are passive in nature; the dominant character of global flow is determined by the Ekman layers. The zonal mean flow field is characterized by a triple-cell structure which consists of two dominant cells and a weak central cell. The similarities and discrepancies between the results of the present model and of the conventional rotating annulus model are delineated.

ISSN:0309-1929    

DOI:10.1080/03091929208229047

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The normal mode instability problem for a stationary Rossby wave of finite amplitude and arbitrary orientation in a two-level model with zonal mean shear in the vertical is examined on the infinite beta-plane using a Floquet technique. The results are compared to the instability of a finite amplitude stationary Rossby wave in a barotropic model. The instability of the barotropic model linearized about the upper level flow of the stationary two-level Rossby wave is also examined; forcing must be introduced to the barotropic equations in this case to balance the time tendency of the basic state.

ISSN:0309-1929    

DOI:10.1080/03091929208229048

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

we report the results of experiments on the spin-up of two layers of immiscible fluid with a free upper surface in a rotating cylinder over a wide range of internal Froude numbers. Observations of the evolution of the velocity field by particle tracking indicates that spin-up of the azimuthal velocity in the upper layer take much longer than in a homogeneous fluid. Initially, spin-up occurs at a rate comparable to that of homogeneous fluid but, at high internal Froude number, a second phase follows in which the remaining lative motion decays much more slowly. Quantitative comparison of these measurements to the theory of Pedlosky (1967) shows good agreement.

ISSN:0309-1929    

DOI:10.1080/03091929208229049

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper is concerned with large-amplitude flows of a two-layer fluid on the β-plane. The Rossby numberε is small, while the displacement of the interface and the depth of the upper layer are both of the order of the total depth of the fluid. Two systems of equations are derived, corresponding to two asymptotic ranges of the parameter β/ε (where β is the ratio of the deformation radius to the earth's radius). With the help of the equations derived, the stability of parallel density-driven flows is examined. It is shown that all flows are unstable with respect to the perturbations with wave length being of the order of the deformation radius.

ISSN:0309-1929    

DOI:10.1080/03091929208229050

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

It is shown that all one-layer geostrophic isolated fronts are stable regardless of their profiles.

ISSN:0309-1929    

DOI:10.1080/03091929208229051

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An analytical boundary layer solution is developed for barotropic, steady, frictional, wind-driven flow over a meridionally aligned top-hat ridge in a circumpolar basin on a local β-plane. Classical Sverdrup dynamics cannot hold in a basin with no meridional barriers. With a top-hat ridge, frictional boundary layers exist adjacent to the depth discontinuities which can support along- and cross-ridge transport. The boundary layers thus provide a mechanism for transporting fluid across latitudes of zero wind stress curl. The relevance of this simple model to the dynamics of the Southern Ocean is discussed.

ISSN:0309-1929    

DOI:10.1080/03091929208229052

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We study numerically the two dimensional linear instabilities of an incompressible, inviscid, density stratified, symmetric jet as a function of a width parameter,D.In the limit of infiniteD, the maximum growth rate of temporal instability exponentially approaches that of the shear flow on either flank of the jet. The growth rate need not approach this limit monotonically, however. For some stratified flows it is possible that the odd (varicose) mode of a jet with sufficiently large width may grow more rapidly than the even (sinuous) mode. We also examine spatiotemporal instabilities of the Bickley profile, focusing specifically upon the identification of the regime of parameter space in which the flow is absolutely or convectively unstable. Finally, our methods of spatiotemporal linear stability analysis are applied to a more realistic asymmetric jet which mimics the internal wave related flow that develops in the lee of a topographic obstacle when “breaking” occurs. This analysis appears to bear strongly upon the interaction that occurs subsequent to wave breaking that leads to intense wave, mean-flow interaction.

ISSN:0309-1929    

DOI:10.1080/03091929208229053

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A two-dimensional numerical model is used to investigate the nonlinear dissipative interaction between a disturbance and an unbounded stratified shear flow. The disturbances considered are Kelvin-Helmholtz instabilities and forced gravity waves. The nonlinear stabilization (destabilization) of Kelvin-Helmholtz instabilities at Prandtl number,Pr< 1 (Pr> 1), found by Brownet al.(1981) is recovered. The model confirms that it is mostly due to a stabilization (destabilization) of the mean flow by the wave. The nonlinear evolution of instabilities existing when thermal dissipation is large and when the Richardson number is everywhere larger than 0.25 is also investigated. It is shown that such a mode stops growing when the nonlinear distortion of the mean flow becomes significant.

ISSN:0309-1929    

DOI:10.1080/03091929208229054

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We establish a nonlinear stability result for convection in a generalized incompressible fluid. Both numerical calculations and an asymptotic analysis are carried out. The linear and nonlinear results are shown to be very close in both cases, implying that the region of possible subcritical instabilities is very small.

ISSN:0309-1929    

DOI:10.1080/03091929208229055

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Numerical simulations of dynamo action are presented for a fluid stirred by a body force such that in the absence of the magnetic field, an ABC flow (to be viewed as the superposition of three helical modes of same wavenumberk0), establishes for kinetic Reynolds numbers below a critical value.

ISSN:0309-1929    

DOI:10.1080/03091929208229056

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor