Underground Rivers - University of New Mexico

Singularities
Chapter 15 -- The Maelstrom
CHAPTER 15
THE MAELSTROM
A mathematical "singularity" is a point at which a
mathematical object fails to be well-behaved. If the
mathematical object were the direction of a compass
needle, it would point straight ahead as one walked
toward the north magnetic pole, but flip when passing
over that point. The pole is thus a magnetic
singularity.
A whirlpool (a "vortex" in hydraulic jargon, a "maelstrom" in
literature) represents another natural singularity.
Conservation of angular momentum causes the water to spin
faster and faster as the radius decreases. In crossing the
center, the direction of flow shifts from right to left. The
center represents a singularity.
Both singularities exist in the earth's polar region. One is
indeed due to an underground river; the other is not. But
which?
Compass Direction
Ahead Behind
There are two general types of whirlpools -- those caused by water drawn down a drain and those
caused by deflection. The millennia-old cultural association between underground rivers and
whirlpools is largely due to not recognizing the difference.
A bathtub drain whirlpool is caused by a subsurface outflow.
Absent another outside force such as the direction of the inflowing
water, water will rotate counterclockwise north of the equator and
clockwise south of the equator, the Coriolis effect named after
Gaspard-Gustave Coriolis, who described it in 1835. Once this
begins, centrifugal force drives the water to the outside and a
cavity forms into which floating objects descend. The Coriolis
effect is extremely slight, however, and the effect of almost
anything will be greater, setting the whirlpool's direction.
The most powerful "natural" whirlpools are the result of fast-flowing tidal waters through narrow
and shallow straits. Unlike the bathtub, however, there is no lower outlet. A related phenomenon
can be seen along a riverbank where a rock or fallen tree branch creates an eddy.
We will take a look at a particular maelstrom long the subject of speculation.
DRAFT 1122//66//22001122
3 2 1 0 -1 -2 -3
Distance from Pole
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