ring vortex

For many purposes a ring vortex may be approximated as having a vortex-core of small cross-section.

When the air converges, to maintain potential vorticity, the air speed increases, resulting in a stretched ring vortex.

The high velocity jet leaving the back of the engine has an inherent shear layer instability (if not thick enough) and rolls up into ring vortices.

Now, the concept I envision treats each ring vortex as a "quasi-particle" and the sponge as a super-imposed "medium" on the base medium.

It was only AFTER we had settled on the ring vortex and superfluid did we even bother to research this topic.

Just like you can study a smoke ring vortex, or you can study how sound propogates or how waves move across the ocean.

Now the vortex ring (smoke ring vortex), if formed in a inviscid perfect fluid, becomes "permanent" and cannot be dissipated (See Helmholtz's theorem).

In these whistles, the flow instability is symmetric, often resulting in periodic ring vortices and the sound generation is associated with fluctuations of volumetric (mass) flow rates.

Data from the crash of Delta Flight 191 near Dallas during a thunderstorm on Aug. 2, 1985, are now part of several training programs for airline pilots and helped set the Federal Aviation Administration's policy on a particular kind of wind shear called ring vortices.