Daily Entropy: the vortex ring

A V-22 Osprey crashed in a vortex ring state

At first glance it is not obvious why the vortex ring state is entropic. But vortices are the natural expression of entropy in fluid mechanics. Vortices are responsible for inefficiency in turbines and propellers and combustion chambers because a vortex is fluid accelerating in all directions at once, so whatever energy created the vortex is wasted and not available to power your machine. A vortex ring starts out as an innocent wingtip vortex, but instead of escaping the rotor and wasting away, the descending helicopter catches the vortex with successive rotor strokes and that power makes it grow until it envelopes the whole rotor and the helicopter goes into free fall.  Increasing power increases the size of the ring but doesn’t slow the descent. This is the fluid mechanical equivalent of a thermal system at maximum entropy – where the heat sink is at maximum capacity.

Vortex ring state is a graphic illustration of catastrophic failure due to entropy.  It also shows that entropy behaves the same way in all of its forms, whether radiation, vibration, dispersion, vortex, expansion, or information.  The vortex ring also shows how hard it is to measure waste of any kind.  This helicopter is producing waste in the form of heat, internal vortices, soundwaves, in addition to that big vortex and the innumerable little vortices spinning off from it and breaking down into waves and random movements – and the craziest part, in storing and processing the information that makes the helicopter work in the first place (or would have made it work if it wasn’t stuck in a vortex ring state).  All of these forms of entropy are linked in this poor helicopter, and they show the poverty of the statistical model for calculating entropy in the real world.  The paradox of waste accounting is that waste can’t even be measured.

The vortex ring state may seem trivial if you are not in a helicopter, but it is a clear, visual representation of the catastrophic drug war and other instances of runaway entropy.   In the war on drugs, additional money fighting drug dealers has no impact on supply, demand or distribution, all of which are completely flexible.  What that effort does is increase the incentives for the industry by eliminating their competition and increasing the market price.  Every time a competitor is eliminated, a market opens with pent-up demand.  This is similar to a drowning non-swimmer whose efforts all go nowhere.  It is also true of the Trump supporters who feel like they are working harder for less in an economy approaching maximum entropy.  The elites are, in fact, responsible for this, and they are blissfully blind to their contributions to entropy.  It seems likely that this cycle of entropy maximisation and political upheaval has repeated itself invisibly throughout history, disguised as war, famine and slavery.


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