I have been asking about volcanoes lately. …
Volcanoes and Fluid hammer
Water hammer is associated with the noisy plumbing characteristics of old houses. And old houses tend to have leaky taps. This is because old taps wear away and or form lime deposits on the seals and or both, the lime causing uneven erosion.
When a tap is closed the rate of water through put changes from several gallons a minute (overall potential in all taps) to something like half a pint every three or four hours (for pretty obvious) dripping taps.
After a short period of slowing down in the pipes the water settles down to the near steady drain the system has got used to. This in all probability becomes the house's harmonic. The internal backflow rate in the eddy set up between flushing and dripping is, nominally:
0.125 gallons per 4 hours (240 min) = 0.0005 gallons per minute; as opposed to 4 gallons a minute.
It's possible to work out the size of the pipe work but most people could guess as they use 1/2 for sinks and toilet cisterns and 3/4 for baths. All you need do is measure the approximate lengths of the floors to guess pipe runs, bearing in mind they will tend to take direct routes from the mains to the main distribution points -boilers etc.
I've ignored central heating.
0.0005 of 1 gallon is quarter of 4 gallons so the ratio of flow from full on to almost fully off is some 0.0001. That's about one ten thousandth of the potential.
Now apply it to a volcanic eruption.
We don't know the potential discharge of a volcano but the worst eruptions are pretty dramatic and the ash cloud can be fairly well guestimated from data collection points, satellite film and computer models. We can guess the approximate discharge of a caldera when the main vent is sealed form pretty much hands on measurements.
So we can gauge an approximate comparison. Let us assume the major volcanic eruptions from time to time are nearly maxed out and that vents provide 0.0001 of the emission that is possible. We don't know what is being lost to underground streams (if any) or is being added to, by heavy rain (which is common with massive eruptions.)
So it all very much a Mind Game.
Volcanic vents are blocked by the deposition of newly formed rock. It comes from the gas/water/debris mix or just from mass surges of molten matrix. There must be quite some oscillation going on when the caldera is open. I wonder if anyone has postulated Reynolds Numbers for that.
When it is finally slowed from its seiche to a magma hammer, the periodicity is now roughly what the constant wear and tear of volcanic formation created. And any changes in the Almost Stillness creates the sound reflected. (Because the opening is no longer acting as an Helmholtz resonator) the harmonic is occasionally (more often than previously) exactly that of the chamber.
When that happens or when the weather changes the magma can heat up in the vibration. (Infrasound used in jewellery baths etc can cause the oils used in them to get very warm.)
But the weather has to be just so in a variety of places at just the right distance to be ducted to the centre of the mountain.
Or not as the case may be.
Whatever the likelihood or unlikelihood, I know I can write it more clearly than that. And in the years to come you may see me do so till it bores you to tears.
The Reynolds number of fluid flow is a comparison of resistances to the flow. The main protagonists are the size of the obstruction (or diameter of the pipe) and the viscosity of the fluid.
For aircraft design the viscosity of air is 13 times less than water at ambient temperatures at sea level. This is a nonsense as planes don't fly at ambient temperatures and seldom at sea level.
For magma, the chamber size is constantly changing and the plasticity of the magma varies within the column at any one time and with the weather all the time.
But if people can work on aircraft fluid flows, what's the problem?
The key to the fluid flow velocities is much the same sort of deduction. If such is worth knowing for any reason.
I have not had a chance to think about that aspect yet.
And anyway, it is hyperbole wrapped up in day dreams about hypotheses built on what-ifs that I'm not sure of.