Laboratory model of two-dimensional polar beta-plane turbulence

2007 ◽  
pp. 285-297 ◽  
Author(s):  
G. F. Carnevale ◽  
A. Cenedese ◽  
S. Espa ◽  
M. Mariani
Keyword(s):  
Laboratory Model ◽  
Two Dimensional ◽  
Beta Plane

Two Dimensional Polar Beta Plane Turbulence

2008 ◽  
pp. 673-675
Author(s):  
G. Carnevale ◽  
A. Cenedese ◽  
S. Espa ◽  
M. Mariani
Keyword(s):  
Two Dimensional ◽  
Beta Plane

Three-Dimensional Scour Below Pipelines

1988 ◽  
Vol 110 (4) ◽  
pp. 373-379 ◽  
Author(s):  
J. Fredso̸e ◽  
E. A. Hansen ◽  
Y. Mao ◽  
B. M. Sumer
Keyword(s):  
Three Dimensional ◽  
Essential Element ◽  
Laboratory Model ◽  
Span Length ◽  
Two Dimensional ◽  
Practical Application ◽  
Field Situation ◽  
Scour Holes ◽  
The Individual ◽  
A Current

This paper deals with the scour below pipelines exposed to a current. In a typical field situation, the scour pattern along a pipeline is not uniform; the scour holes are interrupted with the reaches where the pipeline is partially or totally buried. This paper focuses on the longitudinal extent of the individual scour holes. A simplified picture of the process is given to describe the longitudinal dimension of a scour hole. The sagging of the pipeline is an essential element of the process. The effect of sagging on the final scour depth is investigated, using a two-dimensional laboratory model. A simple equation to calculate the length of individual scour holes (the span length) is developed. The practical application of the equation is demonstrated by an example.

The ‘colour polarigraph’ -a simple method for determining the two-dimensional distribution of sugar concentration

1981 ◽  
Vol 109 ◽  
pp. 277-282 ◽  
Author(s):  
Barry R. Ruddick
Keyword(s):  
Weight Fraction ◽  
Sugar Concentration ◽  
Laboratory Model ◽  
Two Dimensional ◽  
Simple Method ◽  
Dimensional Distribution ◽  
Diffusive Effects ◽  
Visual Record ◽  
Double Diffusive ◽  
Horizontal Layers

A method is described for photographically recording the two-dimensional distribution of sugar concentration in a tank, which typically yields a resolution of 0·01 in weight fraction sugar. The tank image is coloured according to the sugar concentration, giving a quantitative visual record of sugar contours. The technique is demonstrated in photographs of a laboratory model of an oceanic front, in which interleaving quasi-horizontal layers are formed by double-diffusive effects.

Two-dimensional turbulence above topography

1976 ◽  
Vol 78 (1) ◽  
pp. 129-154 ◽  
Author(s):  
Francis P. Bretherton ◽  
Dale B. Haidvogel
Keyword(s):  
Kinetic Energy ◽  
Large Scale ◽  
Two Dimensional ◽  
Constant Depth ◽  
The North ◽  
Beta Plane ◽  
Two Dimensional Flow ◽  
Large Scale Flow ◽  
Quadratic Integral ◽  
North And South

In a turbulent two-dimensional flow enstrophy systematically cascades to very small scales, at which it is dissipated. The kinetic energy, on the other hand, remains at large scales and the total kinetic energy is constant. Above random topography an initially turbulent flow tends to a steady state with streamlines parallel to contours of constant depth, anticyclonic around a bump. A numerical experiment verifies this prediction. In a closed basin on a beta-plane the solution with minimum enstrophy implies a westward flow in the interior, returning in narrow boundary layers to the north and south. This result is interpreted using a parameterization of the effects of the eddies on the large-scale flow. The numerical solution is in qualitative agreement, but corresponds to a minimum of a more complex measure of the total enstrophy than the usual quadratic integral.

scholarly journals Non-ergodicity of inviscid two-dimensional flow on a beta-plane and on the surface of a rotating sphere

1987 ◽  
Vol 184 ◽  
pp. 289-302 ◽  
Author(s):  
Theodore G. Shepherd
Keyword(s):  
Phase Space ◽  
Domain Size ◽  
Finite Amplitude ◽  
Two Dimensional ◽  
Planar Case ◽  
Rotating Sphere ◽  
Dimensional Flow ◽  
Beta Plane ◽  
Quadratic Invariants ◽  
Two Dimensional Flow

It is shown that, for a sufficiently large value of β, two-dimensional flow on a doubly-periodic beta-plane cannot be ergodic (phase-space filling) on the phase-space surface of constant energy and enstrophy. A corresponding result holds for flow on the surface of a rotating sphere, for a sufficiently rapid rotation rate Ω. This implies that the higher-order, non-quadratic invariants are exerting a significant influence on the statistical evolution of the flow. The proof relies on the existence of a finite-amplitude Liapunov stability theorem for zonally symmetric basic states with a non-vanishing absolute-vorticity gradient. When the domain size is much larger than the size of a typical eddy, then a sufficient condition for non-ergodicity is that the wave steepness ε < 1, where ε = 2√2Z/βU in the planar case and $\epsilon = 2^{\frac{1}{4}} a^{\frac{5}{2}}Z^{\frac{7}{4}}/\Omega U^{\frac{5}{2}}$ in the spherical case, and where Z is the enstrophy, U the r.m.s. velocity, and a the radius of the sphere. This result may help to explain why numerical simulations of unforced beta-plane turbulence (in which ε decreases in time) seem to evolve into a non-ergodic regime at large scales.

Sign in / Sign up

Export Citation Format

Share Document