Dangers at the World's Deepest Cave

[jedishrfu]

TL;DR Summary

The dangers of caving at the world's deepest cave.

 

[Vanadium 50]

Maybe you could post a summary?

 

[jedishrfu]

Yes, the video talks about the deepest cave found so far at 7000 ft and about folks who have ventured there, and the water hazards they faced. A small amount of surface rain produced torrents of water flooding the cave system.

 

[dlgoff]

Dang. You wouldn't catch me in there. 7257 feet (2212 m) deep.

 

[Drakkith]

I was just watching some videos and looking up some information on Veryovkina Cave a few days ago. Interesting that this video was posted soon after lol.

 

[anorlunda]

Dang. You wouldn't catch me in there. 7257 feet (2212 m) deep.

I'll second that. Visualize water falling down a vertical shaft. It would not be isolated drops. so I'm not sure what the terminal velocity would be. Whatever, it sounds pretty fatal to me.

 

[anorlunda]

I've been trying to imagine modeling the water falling in that 2000 m deep cave. The complexities make my head hurt, even for the simplified case with a smooth vertical shaft.

• As the stream of water falls down, there must be a current of air flowing up. There would be a boundary layer and a core layer in the water stream.
• Terminal velocity of independent falling drops would not apply. I don't know how to calculate terminal velocity for this geometry.
• Would the tip of the water stream be bullet shaped, as in a river, or mushroom shaped?
  
  
• A critical parameter is the difference in shaft radius R_s, and water stream radius R_w. Imagine an annular shape for the rising air. As (R_s-R_w) approaches zero, the falling stream becomes a piston compressing the air below, and decelerating the water.
• Air below the water would be compressed. For a shaft that deep, fantastic pressures in the range of 100-200 bar are possible. Might the rising air even go supersonic?
• Energy stored compressing the air would rebound. That might cause the falling water to reverse direction and become a geyser. It could even be oscillatory.
  
• The rising air might take the form of bubbles, rather than a continuous annular flow. The whole thing might resemble gurgling water coming out of an upside down bottle.
  

It sounds like the magnitude of comprehensive modeling exploring the full range of parameters, might be a PhD thesis, or even a lifetime of work. It might be thankless work because few people other than spelunkers would be interested.

But one thing is abundantly clear without models. It is amazing that nobody died in this incident.

 

[jedishrfu]

Actually, someone did die. In a separate incident, a lone caver went in and couldn't get out.

https://www.dailymail.co.uk/news/ar...h-worlds-deepest-cave-reclaimed-team-100.html

He's mentioned in the video I posted in another thread where they said he had descended about 3000ft into the cave and was stopped when he realized he couldn't get past the water issues below.

While he had hand ascenders, he didn't have ascender stirrups for his feet and couldn't ascend the rope to get out and died from exhaustion.

 

[dlgoff]

While he had hand ascenders, he didn't have ascender stirrups for his feet and couldn't ascend the rope to get out and died from exhaustion.

I saw that part of the video. Poor guy. :(

 

[256bits]

I've been trying to imagine modeling the water falling in that 2000 m

Similar to a waterfall no doubt - misty, huge droplets, air entrained.

One can turn on a tap and see the flow thin out and break up into droplets due to acceleration due to gravity and surface tension.
Just put several thousand of these taps together and investigate to flow.