Trajectories of Vortex Lines Beneath a Free Surface of Above a Plane

1989 ◽  
pp. 275-283
Author(s):  
B. Yim
Keyword(s):  
Free Surface ◽  
Vortex Lines

Free Surface of a Rotating HeII Film

1973 ◽  
Vol 51 (21) ◽  
pp. 2283-2286 ◽  
Author(s):  
E. Vittoratos ◽  
M. W. Cole ◽  
P. P. M. Meincke
Keyword(s):  
Thin Films ◽  
Free Surface ◽  
Superfluid Helium ◽  
Vortex Line ◽  
Rotational Frequency ◽  
Experimental Results ◽  
Quantized Vortex ◽  
Bulk Liquid ◽  
Vapor Interface ◽  
Vortex Lines

Stimulated by recent conflicting experimental results, we have investigated the properties of quantized vortex lines in thin films of superfluid helium. The shape of the liquid–vapor interface in the presence of a single line is calculated. The depression of the interface ("dimple") that results is considerably smaller for the film than for the bulk liquid. The critical rotational frequency for the appearance of the first vortex line is only slightly reduced below the bulk value.

The viscous vortex induced by a sink on the axis of a circulating fluid in the presence of a plane free surface

1969 ◽  
Vol 36 (2) ◽  
pp. 219-238 ◽  
Author(s):  
T. J. Pedley
Keyword(s):  
Reynolds Number ◽  
Free Surface ◽  
Stagnation Point ◽  
Velocity Fields ◽  
First Order ◽  
The Core ◽  
Meridional Velocity ◽  
Vortex Lines ◽  
Burgers Vortex ◽  
Made In

The flow under discussion represents an idealization of the bath-tub vortex; distortions of the free surface, finite sink size, and all rigid boundaries have been eliminated from the problem in order to isolate the effect of the non-uniform stretching of vortex lines produced by the sink flow. A boundary-layer type of approximation is made about the axis, which requires that the meridional Reynolds number (N) be large, and since the problem is still intractable, an expansion is made in powers ofK=R2/N(whereRis the swirl Reynolds number), which measures the strength of the interaction between the swirl and meridional velocity fields. In the limit of zeroKthe flow is a modified Burgers vortex whose radius decreases to zero at the sink. For non-zeroK, the interaction is not restricted to the vortex core, because the presence of the vortex modifies the outer irrotational flow, inducing a radial mass flux into the core, whose dependence on the axial co-ordinate is calculated to the first order inK.The structure of the core is obtained, again to the first order inK, from two co-ordinate expansions, one near the stagnation point on the axis, and the other near the sink, although only the first few terms of the latter can be determined explicitly. It is shown how the methods can be extended not only to higher orders inK, but also to any other narrow viscous vortex in which the vortex lines are stretched non-uniformly away from an internal stagnation point.

Geometry Effects on Free Surface Vorticity Flux

1999 ◽  
Vol 121 (3) ◽  
pp. 678-683 ◽  
Author(s):  
Bill Peck ◽  
Lorenz Sigurdson
Keyword(s):  
Free Surface ◽  
Convenient Method ◽  
Gaussian Curvature ◽  
Vortex Lines ◽  
Geometry Effects ◽  
Vorticity Flux

Effects of geometry on the flux of vorticity from a free surface are discussed. Special attention is paid to situations where curvature-dependent contributions to the vorticity flux can be neglected. The geometry of vortex lines embedded in the surface is discussed in this context. These results show that vortex lines can be straight and geometry-induced vorticity flux is produced; conversely vortex lines can be curved and no geometry-induced vorticity flux is produced. A convenient method for assessing vorticity flux from a steady surface based on Gaussian curvature is derived.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

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