摘要:

A numerical calculation is described which demonstrates the collision of two quasigeostrophic isolated vortices, of the monopole type. The collision creates an oscillatory dipole structure. The dipole is shown to consist of a nonlinear isolated vortex, of the modon type, and a superimposed fluctuation field. The modon is different from previously known modons, with a nonlinear functional relationship between potential vorticity and streamfunction. The only effect of the fluctuations upon the underlying modon is the induction of changes in the separation distance between the dipole centers, and hence the dipole speed; otherwise, they appear to have the qualitative characteristics of normal modes of the underlying modon. Speculations are presented about the analogy between collisions of isolated vortices and of subatomic particles.

ISSN:0309-1929    

DOI:10.1080/03091928308209055

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A description is given of some experiments made to examine the possible trapping of surface waves by a submerged cylindrical sill in an otherwise uniform ocean. Theories by Longuet-Higgins (1967) and Renardy (1983) indicate that, at certain dangerous frequencies, nearly resonant conditions may obtain, leading to unusually large wavefields over the sill.

ISSN:0309-1929    

DOI:10.1080/03091928308209056

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Experiments on the deepening of a sheared, turbulent, homogeneous layer downwards into a denser, homogeneous layer were conducted in an annular, laboratory tank, similar to, but larger than, that used by Kato and Phillips (1969). It was found that the entrainment rate did not scale on a Richardson Number containing the upper-layer depth as the length scale, but that all two-layer experiments do scale well on the product of a Richardson Number,gΔρW/ρU2, and the ratioU/u*, whereWis a tank dimension and other symbols have their conventional meanings. This result shows that two velocity scales may be necessary to describe turbulent entrainment across a sheared interface.

ISSN:0309-1929    

DOI:10.1080/03091928308209057

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A simple “laboratory” flow is described which exhibits the bistable behavior observed in more complicated geophysical flows. The behavior is present in a blocking experiment involving a shallow, homogeneous flow over an obstacle. It is demonstrated that within a certain parameter space, the blocking tendency depends not only on the heightbOof the obstacle but on the history of the flow as well. The implied hysteresis confirms behavior predicted by Baines and Davies (1980, p. 239). It is further shown that the hysteresis is associated with a nonuniqueness in steady solutions which is, in turn, attributed to the existence of stationary blocking bores upstream of the obstacle.

ISSN:0309-1929    

DOI:10.1080/03091928308209058

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

In a rotating turbulent body of fluid, the turbulent thermal conductivity tensor is essentially latitude-dependent; it thus always gives rise to a latitude dependent surface temperature profile. Yet the resulting pole-equator temperature difference proves to be very small if the (small-scale) eddy conductivity is sufficiently high—as is the case in the bulk of the solar convection zone. The (inconvenient) rapid decrease in turbulent diffusion near the solar surface is overcompensated by the even more rapid decrease in the part of the thermal conductivity tensor that is rotational in origin.

ISSN:0309-1929    

DOI:10.1080/03091928308209059

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0309-1929    

DOI:10.1080/03091928308209054

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor