摘要:

A formulation is presented for barotropic, steady, inviscid flow through a rectangular opening by a rotating fluid. The magnitude of the flow depends on the difference in free surface height δ ζ, force of gravityg, Coriolis parameterf, and opening widthw. It is not necessary for the channel to approach the Rossby radius in width for important rotational effects to be felt. WhenW/w<1 (the ratio of a novel width scaleW=(2gδ ζ)½/fto channel width), the Garrett and Toulany (1982) prediction for mean velocity of=gδζ/fwis found. In the converse limit,=(2gδ ζ)½−½fw. Both are confirmed by laboratory experiment. The laboratory flow approximately matches the assumption that relative vorticity is −f. There are straits in the oceans and flows through mountain passages which may be governed by the laws discussed here.

ISSN:0309-1929    

DOI:10.1080/03091928608210084

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper studies numerically the temporal development of spatial oscillations in a confined rotating fluid differentially heated from below. It is found that spatial oscillations occur when the internal Rayleigh number is larger than the critical Rayleigh number obtained from linear analysis. Because the internal Rayleigh number depends on the vertical temperature gradient and length scale which are time dependent, the stability of the transient flows cannot be predicted from an external Rayleigh number. The numerical resolutions of boundary layers are discussed.

ISSN:0309-1929    

DOI:10.1080/03091928608210085

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The steady solution for the flow in the D” layer given by Stacey and Loper (1983) is generalized and placed on a firmer mathematical foundation. The stability of this flow is then analyzed and a stability criterion is developed. It is found that the stability of the flow is consistent with a lower-mantle viscosity of 0.5–1.0 1023Pas and a temperature jump of 700–800K across the layer, but if the viscosity is only 3–5 1021Pas, stability of the flow requires a much lower temperature jump. If the higher value of viscosity is correct and the flow is believed to be close to marginally stable, this argues against a second thermal boundary layer occurring elsewhere in the mantle.

ISSN:0309-1929    

DOI:10.1080/03091928608210086

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

We propose a new method of solution of the unsteady non-linear Eddington-Vogt-Sweet circulation. We do not use eddy viscosity, in contrast to Tassoul and Tassoul (1982a), and we take the turbulent flow in the radiative region of a rotating main sequence star as an unsteady laminar flow. Analogous to the situation in ordinary gasdynamics (Kawamura and Kuwahara, 1984), results based on our laminar type model of a turbulent flow in a rotating star will complement a series of results by Tassoul and Tassoul for the inner rotation of a star. By employing our method, the following results are obtained. (1) We derive a non-linear partial differential equation of the perturbation as the basic equation of the main bulk of flow in the radiative region. (2) We show that the boundary layer at the interface between the convective and the radiative regions is of the Ekman type. We show ways to resolve the singularity of the meridional velcoity on the interface and give boundary conditions for the main bulk of the flow. (3) We demonstrate that we can construct a non-singular solution which has sufficient degrees of freedom and satisfies the surface boundary conditions of an early type rotating star. We do not need, therefore, a Mestel-Tassoul and Tassoul type surface boundary layer in our treatment. (4) We examine a simple one-dimensional model of our basic equation from the viewpoint of numerical gasdynamics and discuss the astrophysical meaning of the results.

ISSN:0309-1929    

DOI:10.1080/03091928608210087

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In this paper we discuss the large-scale meridional currents and differential rotation in the radiative envelope of a single, nonmagnetic, early-type star. Our solutions depend on the interaction between these large-scale motions and the small-scale baroclinic eddies, which are an ever-present feature of a stellar radiative zone. If one makes allowance for meansteadymotions in a typical rotating star, then large eddy viscosities are necessary for the method to converge. We show that there exists a singular, thermo-viscous boundary layer at the interface between the convective core and the radiative envelope. Unless very unrealistic assumptions are made, this layer isnotof the Ekman type.

ISSN:0309-1929    

DOI:10.1080/03091928608210088

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Poloidal magnetic fields induced by radial flows under spherically symmetric conditions are known to decay pointwise to zero on a diffusion time-scale. We here prove decay to zero on the diffusion time-scale, in an integral sense, of toroidal fields in the same conditions.

ISSN:0309-1929    

DOI:10.1080/03091928608210089

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor