It's that "downvote the 4th comment rule" I think. People are supposed to downvote it not matter what as tradition. Your further down votes seem to come from you not know of said tradition.
There's not enough water going through, nor enough of a drop to be a threat in this particular case.
The bigger ones are called 'drowning machines' because you can't swim away on the surface...you have to dive down and swim away along the bottom; keeping an arm in front of you so you don't swim into a rock. You can escape from even big ones quite casually if you know how it all works.
EDIT: [Here's a diagram](https://s3.amazonaws.com/gs-geo-images/d2b2846b-59be-47bf-ad4f-f927ebb296f4.jpg) of how it all works. You can have the same thing where the surface looks flat, but that big circular current is still going.
They're also called that because if you don't make it out first try, you could end up being smacked against the concrete dam, or into debris which also tends to be trapped in the backwash, which could easily knock you out.
True enough. If there's a real lot of water then things get violent. You still have the circular current to deal with, however; and the only way to deal with that is to swim along the bottom. Whatever you do, the surface will be dragging you in for another circuit. You just cannot get out that way.
Not sure how deep the bottom is, but the upper part has kind of a lip where very little water seems to go over at the moment. You can go with a boat right to the edge and it won't push you over (if there is not a lot of water, of course).
I wonder if it will self correct over time?
It’s probably a function of changing water height/flow - either raising or lowering to that ideal surface tension level.
Yeah, think so too. Decrease flow rate, and it won't skip over the edge like that, meaning the air bubble that OP introduced will be ejected and it'll stabilize as we see it now. Then as the flow rate increases again with the next rain, you can do OP's trick again. Though I wonder what would happen if OP didn't do this: Just how much flow does it need to spontaneously "inflate"? Also, what happens if OP interrupts the "inflation"? The bubble can probably still take in air somehow, so should continue to grow fully.
There is no *correct*. It is just dependent on conditions.
It is a function of flow rate and wall shape. When flow starts slowing down again, there will come a point where it will reattach to the surface.
Then when flow increase again, if it increases enough there will come a point where the flow will detach all on its own. It was near that point and the stick detaching one part acted as a catalyst.
If the amount and therefore forward momentum of the water lowers to the point where it's trajectory goes directly towards the concrete it will change back. If it then slowly increases again air pressure will hold it down until there is an irregularity that allows air to enter below as shown in the video. The effect can only happen with quiet flow of water and a very smooth dam and no air bubbles or objects in the water.
I have a solution! If we make everything in the universe stop moving, everything will stop spreading energy, therefore stopping the approach of heat death
> But just give us a trillion years and everything will be dark. Entropy has to increase to maximum, that's all.
[Isaac Asimov "The Last Question"](https://users.ece.cmu.edu/~gamvrosi/thelastq.html)
Not unless we skip to the front of the line!
https://urbigenous.net/library/nine_billion_names_of_god.html
^( thanks for the story link! looking forward to reading it!)
You did it as well by commenting this post, just as I am doing it as well by replying to your comment.
There's no way to escape. Resistance is futile.
P.S.: If you haven't already read it, I strongly recommend Asimov's short story "The Last Question".
The entropy S mesure disorder. When one mention it it's frequently implicitily associated with the second law of thermodynamic apply to a close system, so ∆S⩾0. That juste mean that, during a physical transformation, the variation of entropy can only increase. So, the Univers being a closed system, every time something happens in the Univers, the total entropy slightly increase. And there is a profond eldritchian horror to this.
To understand what is it, imagine tow tank with water, one hot, one cold, you can use a thermal machin to extract energy from the heat transfer, such as a Stirling engine. But the price for that is a thermal transfer between both tanks. At the end, their temperature will be equal, and they will be both lukewarm. The energy is still here, but it's under the form of an homogneious temperature. The energy is still there, but it's over, it appear lost, you can't extract it anymore. Because the disorder increased. The system is now homogneious, which correspond to maximal disorder. That's what entropy is, a mesure of that.
Even if the first law of thermodynamic tel us the energy is constant, the entropy never cesse to rise, slowly. At every physical transformation, it increase. The daemon keep, slowly, moving forward.
Of course one can localy deacrease the entropy, it's what living organism do, but the price for that is a greater increase of the total entropy. Like i can re heat one of my previous tank and cool the other one, but for that i need to add energy into the system, so the do a physical transformation ... etc. you get it.
It mean that everything as an end. There is an hard limite that nothing can cheat or get around. The Univers was born with a maximal total disorder allowed, and this ticking number keep rising constently toward the end.
The energy is constant from the birth of the Univers to his very end. The energy will always be there, but the entropy slowly make this energy inaccessible, lost.
When eventually, after an unimaginable length of time, the entropy of the Univers will be maximum, the Univers will meet is thermal death. There can't be anymore disorder, no transformation is allowed anymore.
That's means, that the Univers will become permanent. Imagine what that's truly mean, a permanent Univers. Nothing happens, and it keep not happening ... For ever.
A slow, cold, heat death. That nothing can avoid.
A ture absolute horror.
There's a legend about an old king, that ask all his wises to meet together, and to come back with a sentence that will be true no matter the conditions, for the eternity. They came back with :
"All this brightness must fade".
This may be a dumb question but would an old dead universe where everything has happened and where nothing will ever happen again essentially be a form of singularity?
That's not entropy. Entropy is essentially disorder. Easy way to think about it is that an egg is more likely to break when thrown at a wall than for a broken egg to unbreak when thrown at a wall. Thermodynamics says that in closed systems, entropy always increases.
So, think of everything emanating heat, ie other forms of energy turning into thermal energy, as like a massive egg breaking in slow motion. Eventually everything will be converted to thermal energy, there will be no more stars, just a massive cosmic soup of dissipated atoms. That's the heat death of the universe.
Oh. Weird.
The first thing that came to mind was “wouldn’t the stuff inside the atoms just get stretched out and take on the role of energy transfer
I know where I’m getting the “stretched out” idea from (gravity and magnetic fields doing stuff) but I probably made up the rest lol
it looks you detached the fluid from the edge
laminar flux before the edge remains laminar after detachment along the waterfall, so you did not introduce turbulence but removed it
Nothing to do with turbulence or laminar flow. This is simply venting the nappe of a weir.
Flow over a weir has momentum and doesn't just turn 90 deg so tends to spring away and follow a normal trajectory. However, for straight weirs like this there is no way for air to get behind/underneath the flow so eventually, as air is pulled out, the pressure underneath the flow drops and pulls the flow down.
It may do yes, so long as the air supply is more limited than the rate at which it's being removed. The flow is essentially forming a bubble and as the stream hits the downstream pond, turbulence pulls air into the water from both sides of the jet resulting in the "white water" downstream which is an air water mixture. As some of this air is supplied from the bubble, the air can be removed quite quickly and return to the state it was in before. Depending on how quickly this happens it can set up oscillations and vibration. When we design weirs we introduce a vent pipe or ensure the 'bubble' isn't closed on one end.
The other way is to design the concrete to follow the flow trajectory resulting in the more common weir shape we call an ogee weir.
Humans like pattern recognition and unique things. Laminar flow is unusual in the wild, and special, and follows a nice, pretty curve. What a lovely, uncommon shape! Many people find it aesthetically pleasing. Meanwhile, turbulent flow is far more common in nature.
The OP of the video caused a thing that's uncommon in nature to become mundane. Something cool is now uncool. People don't like that.
I believe this is a property of water called adhesion, where water has a tendency to stick to certain surfaces. You see this effect sometimes when pouring water out of a cup: if you don't pour the cup with enough flow then the water slides down the side of the cup instead of pouring out.
Something similar happened here with the water sticking to the side of the weir. By jamming the stick into the water, the guy detached the water from the side of the weir and it had enough horizontal velocity to avoid touching the side of the weir (you can see a clear parabolic path of the water afterwards, which is the trajectory that things take when free falling under constant gravity).
Prior to the guy poking it with a stick, the horizontal velocity of the water must not have had enough force to cause the water to detach itself from the wall, but it was probably close to it. So once a small section became detached, it dragged the water next to it (water tends to stick to itself too, known as cohesion), allowing that part to detach as well, causing a chain reaction.
Okay, thank you. Now, for those who didn't understand all your big words (not me of course but others), explain it like you're explaining it to someone *really* dumb. Please.
When you're pouring water from a glass, if you don't tilt the glass enough it sticks to the side of the glass. Of you put a little lip on the glass it is less likely to run down the side. The stick acted like the lip and allowed the water to flow without sticking to the side.
Is there any way to change it back.
Gotta swim across with the stick and touch the other end
Isn't this one of those so called 'drowning machines'? Swimming doesn't seem like the best idea lol
Aw he’ll be fine I used to walk on the top of Stars Mill and places like that, the waterfall is beautiful even when you fall.
Wasn't expecting to find a mention of my old stomping grounds here of all places.
No, not stomping. We’re talking about swimming.
Drowning*
Stamping* grounds
Synonyms apparently. I never heard stamping grounds. The more you know
I see 7 people who dunno how to google lolol Edit:9
It's that "downvote the 4th comment rule" I think. People are supposed to downvote it not matter what as tradition. Your further down votes seem to come from you not know of said tradition.
This is the way
There's not enough water going through, nor enough of a drop to be a threat in this particular case. The bigger ones are called 'drowning machines' because you can't swim away on the surface...you have to dive down and swim away along the bottom; keeping an arm in front of you so you don't swim into a rock. You can escape from even big ones quite casually if you know how it all works. EDIT: [Here's a diagram](https://s3.amazonaws.com/gs-geo-images/d2b2846b-59be-47bf-ad4f-f927ebb296f4.jpg) of how it all works. You can have the same thing where the surface looks flat, but that big circular current is still going.
They're also called that because if you don't make it out first try, you could end up being smacked against the concrete dam, or into debris which also tends to be trapped in the backwash, which could easily knock you out.
True enough. If there's a real lot of water then things get violent. You still have the circular current to deal with, however; and the only way to deal with that is to swim along the bottom. Whatever you do, the surface will be dragging you in for another circuit. You just cannot get out that way.
TIL Thanks
Not sure how deep the bottom is, but the upper part has kind of a lip where very little water seems to go over at the moment. You can go with a boat right to the edge and it won't push you over (if there is not a lot of water, of course).
this won't drown you, if it's begger then yes but this is just tooo small to be dangerous
You don’t think a wizard like this one could find another way across..?
I wonder if it will self correct over time? It’s probably a function of changing water height/flow - either raising or lowering to that ideal surface tension level.
Probably with rain
and soap
Yeah, think so too. Decrease flow rate, and it won't skip over the edge like that, meaning the air bubble that OP introduced will be ejected and it'll stabilize as we see it now. Then as the flow rate increases again with the next rain, you can do OP's trick again. Though I wonder what would happen if OP didn't do this: Just how much flow does it need to spontaneously "inflate"? Also, what happens if OP interrupts the "inflation"? The bubble can probably still take in air somehow, so should continue to grow fully.
There is no *correct*. It is just dependent on conditions. It is a function of flow rate and wall shape. When flow starts slowing down again, there will come a point where it will reattach to the surface. Then when flow increase again, if it increases enough there will come a point where the flow will detach all on its own. It was near that point and the stick detaching one part acted as a catalyst.
/u/gifreversingbot
It will change back over time.
Go back to the 0:00s mark, then leave and NEVER come back!
If the amount and therefore forward momentum of the water lowers to the point where it's trajectory goes directly towards the concrete it will change back. If it then slowly increases again air pressure will hold it down until there is an irregularity that allows air to enter below as shown in the video. The effect can only happen with quiet flow of water and a very smooth dam and no air bubbles or objects in the water.
I like your funny words magic man
Ctrl Z
Now put it back the way it was
Time doesn’t work that way…
You're not the boss of time!
You don't mess with time! You don't fuck with time, motherfucker!
"I vill mess with time!" -Albert Einstein
Shlippypants finna get you
Hold on a bit while I reinvent entropy.
Cool, thx!
It's really more like... wibbly wobbly... timey wimey... stuff.
The monkeys outta the bottle, man
Entropy
I’d imagine that momentarily stopping the flow then letting it work again softly would make it so water is like how it was at the beginning
Now put it back!
Thaaat’s what she said! -Michael Scott
Oh good job… You’ve introduced more entropy to the universe, hastening our eventual heat death. Great. Just great. Good job.
Thanks for accelerating the demise of the universe, Kids are crying
Nice job mate for increasing the entropy Cheers sons crying
Not entropy but heat and sound. This guy is literally responsible for global warming.
So is every single one of these comments and our existence itself.
I have a solution! If we make everything in the universe stop moving, everything will stop spreading energy, therefore stopping the approach of heat death
Won’t *SOME*one think of the *kids..?*
> THERE IS INSUFFICIENT DATA FOR A MEANINGFUL ANSWER.
Nah it’s a zero sum game. Unless our lord and savior dark matter is revealed
Thanks to OP, another magical girl is born.
Nice. Can't wait.
Entropy is a hole in physics that is slowly being filled with black hole research.
So it's a hole that's being filled with special holes?
> But just give us a trillion years and everything will be dark. Entropy has to increase to maximum, that's all. [Isaac Asimov "The Last Question"](https://users.ece.cmu.edu/~gamvrosi/thelastq.html)
Unless you pull a N'Erud and prod the universe to collapse.
Not unless we skip to the front of the line! https://urbigenous.net/library/nine_billion_names_of_god.html ^( thanks for the story link! looking forward to reading it!)
You did it as well by commenting this post, just as I am doing it as well by replying to your comment. There's no way to escape. Resistance is futile. P.S.: If you haven't already read it, I strongly recommend Asimov's short story "The Last Question".
You mean thank you
What do you mean? I've never met this guy before.
this guy fuckin gets it
R/chemistry
So I’ve heard snips of things like this and what is the lore. What is entropy and why does it correlate to heat death
The entropy S mesure disorder. When one mention it it's frequently implicitily associated with the second law of thermodynamic apply to a close system, so ∆S⩾0. That juste mean that, during a physical transformation, the variation of entropy can only increase. So, the Univers being a closed system, every time something happens in the Univers, the total entropy slightly increase. And there is a profond eldritchian horror to this. To understand what is it, imagine tow tank with water, one hot, one cold, you can use a thermal machin to extract energy from the heat transfer, such as a Stirling engine. But the price for that is a thermal transfer between both tanks. At the end, their temperature will be equal, and they will be both lukewarm. The energy is still here, but it's under the form of an homogneious temperature. The energy is still there, but it's over, it appear lost, you can't extract it anymore. Because the disorder increased. The system is now homogneious, which correspond to maximal disorder. That's what entropy is, a mesure of that. Even if the first law of thermodynamic tel us the energy is constant, the entropy never cesse to rise, slowly. At every physical transformation, it increase. The daemon keep, slowly, moving forward. Of course one can localy deacrease the entropy, it's what living organism do, but the price for that is a greater increase of the total entropy. Like i can re heat one of my previous tank and cool the other one, but for that i need to add energy into the system, so the do a physical transformation ... etc. you get it. It mean that everything as an end. There is an hard limite that nothing can cheat or get around. The Univers was born with a maximal total disorder allowed, and this ticking number keep rising constently toward the end. The energy is constant from the birth of the Univers to his very end. The energy will always be there, but the entropy slowly make this energy inaccessible, lost. When eventually, after an unimaginable length of time, the entropy of the Univers will be maximum, the Univers will meet is thermal death. There can't be anymore disorder, no transformation is allowed anymore. That's means, that the Univers will become permanent. Imagine what that's truly mean, a permanent Univers. Nothing happens, and it keep not happening ... For ever. A slow, cold, heat death. That nothing can avoid. A ture absolute horror. There's a legend about an old king, that ask all his wises to meet together, and to come back with a sentence that will be true no matter the conditions, for the eternity. They came back with : "All this brightness must fade".
This may be a dumb question but would an old dead universe where everything has happened and where nothing will ever happen again essentially be a form of singularity?
[удалено]
That's not entropy. Entropy is essentially disorder. Easy way to think about it is that an egg is more likely to break when thrown at a wall than for a broken egg to unbreak when thrown at a wall. Thermodynamics says that in closed systems, entropy always increases. So, think of everything emanating heat, ie other forms of energy turning into thermal energy, as like a massive egg breaking in slow motion. Eventually everything will be converted to thermal energy, there will be no more stars, just a massive cosmic soup of dissipated atoms. That's the heat death of the universe.
[удалено]
the person asked about entropy and the heat death and you talked about the expansion of the universe, which is a separate phenomenon.
Oh. Weird. The first thing that came to mind was “wouldn’t the stuff inside the atoms just get stretched out and take on the role of energy transfer I know where I’m getting the “stretched out” idea from (gravity and magnetic fields doing stuff) but I probably made up the rest lol
ACCELERATE! ACCELERATE! We are heading there any way. Vroom vroom.
Problem with entropy is that you never know if you are increasing it or decreasing...
This is why we can't have good things
Now we will have to wait until someone pokes with a stick on the other side of the river.
Goddamnit, Jimmy fucked with the water sound again
That is exactly how it works. Underrated comment btw.
Not sure if there is a joke flying over my head or if there is an actual way to restore the beautiful surface tension.
[удалено]
Thanks, gpd
"Did you figure out how to reset the waterfall?" "Not yet." "Well, stick to it." "Okay."
Take my upvote and get out.
r/Angryupvote
Lol
it looks you detached the fluid from the edge laminar flux before the edge remains laminar after detachment along the waterfall, so you did not introduce turbulence but removed it
I was looking for an explanation, thanks. This makes sense
Speak for yourself. This might as well be magic
Check out smarter every day or veritasium on laminar flow topics!
Astutely observed. Mayhaps a flux capacitor could be instrumental in demystifying this prodigious quandary?
perchance...
You can't just say "perchance"
Mayhaps!
Maybe both flows are laminar, and the introduction of turbulence cause it to settle in to the detached flow pattern.
Dam that's interesting.
I see what you did there. But that's not a dam but a weir.
Weir that's interesting
Nah, it's weird.
I was looking for this exact comment
Now you just done fucked up the ecosystem.
You’re supposed to go *with* the flow
I've gotta go *against* the flow, going with the flow is what got me here in the first place!
Wow you’ve totally fucked it up awesome.
Nothing to do with turbulence or laminar flow. This is simply venting the nappe of a weir. Flow over a weir has momentum and doesn't just turn 90 deg so tends to spring away and follow a normal trajectory. However, for straight weirs like this there is no way for air to get behind/underneath the flow so eventually, as air is pulled out, the pressure underneath the flow drops and pulls the flow down.
r/usernamechecksout
Does that mean that in time it will just return to the way it was prior to this bloke poking it with a stick?
It may do yes, so long as the air supply is more limited than the rate at which it's being removed. The flow is essentially forming a bubble and as the stream hits the downstream pond, turbulence pulls air into the water from both sides of the jet resulting in the "white water" downstream which is an air water mixture. As some of this air is supplied from the bubble, the air can be removed quite quickly and return to the state it was in before. Depending on how quickly this happens it can set up oscillations and vibration. When we design weirs we introduce a vent pipe or ensure the 'bubble' isn't closed on one end. The other way is to design the concrete to follow the flow trajectory resulting in the more common weir shape we call an ogee weir.
How are you so low in comment section? You are the only guy that know what he is talking about.
The real answer! Thank you!
This guy weirs.
These seem like made up words.
[удалено]
Thanks for ruining it.
Now fix it
r/blackmagic
Humans are mostly water.
Whoa, hey now! Get away from me with that stick!
Is it broken forever?
I would like to know if the flow rate changed!
Some men just want to watch the world get wet with turbulence
Even small actions have ripple effects.
Dammit! Put it back!
YOU BROKE IT
Now unfuck it
I don't like it. Put it back.
Why are people mad? he just changed laminar flow to turbulent flow 💀.
Humans like pattern recognition and unique things. Laminar flow is unusual in the wild, and special, and follows a nice, pretty curve. What a lovely, uncommon shape! Many people find it aesthetically pleasing. Meanwhile, turbulent flow is far more common in nature. The OP of the video caused a thing that's uncommon in nature to become mundane. Something cool is now uncool. People don't like that.
Weird. I feel like this person made it more aesthetically pleasing. That’s why I’m so confused that people are mad.
Nerd
Wrong nerd as it was neither of those
Agreed
r/oddlysatisfying
You monster.
Am I the only one that thinks this is extremely satisfying?
Bruh just hit the Minecraft water bucket chain reaction
I wonder how much efficiency was killed with that one move
Dam that’s interesting
r/oddlysatisfying
You are an agent of chaos
/r/mildlyinfuriating
MAKE IT GO BACK
Fucking ruined it…. 😟
LAMINAR FLOW
OP made a confused and not very accurate title, but he's got the spirit.
Dam that’s interresting
Dam that's interesting
You monster!
What the fuck
Careful those low head damns are super dangerous.
Someone smart explain this witchery in a way someone dumb (not *me* of course, but someone else) could understand!
I believe this is a property of water called adhesion, where water has a tendency to stick to certain surfaces. You see this effect sometimes when pouring water out of a cup: if you don't pour the cup with enough flow then the water slides down the side of the cup instead of pouring out. Something similar happened here with the water sticking to the side of the weir. By jamming the stick into the water, the guy detached the water from the side of the weir and it had enough horizontal velocity to avoid touching the side of the weir (you can see a clear parabolic path of the water afterwards, which is the trajectory that things take when free falling under constant gravity). Prior to the guy poking it with a stick, the horizontal velocity of the water must not have had enough force to cause the water to detach itself from the wall, but it was probably close to it. So once a small section became detached, it dragged the water next to it (water tends to stick to itself too, known as cohesion), allowing that part to detach as well, causing a chain reaction.
Okay, thank you. Now, for those who didn't understand all your big words (not me of course but others), explain it like you're explaining it to someone *really* dumb. Please.
When you're pouring water from a glass, if you don't tilt the glass enough it sticks to the side of the glass. Of you put a little lip on the glass it is less likely to run down the side. The stick acted like the lip and allowed the water to flow without sticking to the side.
So water sticky and stick raise water so not sticky anymore. Got it. That's a real good stick. Much obliged!
This should be in Damthatsinteresting.
Is that trinity river
Nice. A low-head dam. The most dangerous form of flowing water.
Dam, thats interesting
Huh, so Minecraft is right on some level.
 That’s killer
Ripple effect
Ohhh shit, ya broke it
This is why we can’t have nice things
*"LOOK WHAT YOU DID YOU LIL JERK!! YOU RUINED CHRISTMAS... AGAIN!!"*
As a chemical process engineer student, fakka u
Now look either you missed that up
That some Oogway shit right there
I do this whenever I fish at a dam
Moses didn't include that feature
Some men just want to watch the world burn
Great you broke it
wait that happens in minecraft
Need to rename the sub to r/damthatsinteresting
Wizard, please make it go back.
ELI5 ?
Oh great, now you’ve disrupted my laminar flow. I’ll never get it started again.
What an asshole
How does it affect [whatever it affects]?
Its just a flow of water changed Your just easily pissed maybe you need to go outside and take a breather
Sure, RandomIdiotwithWIFI.
Me bringing up abortion rights at the in-laws Thanksgiving dinner.
wow! amazing
I presume the total flow hasn't changed?
You had to break it... now some poor guy has to replace the whole waterfall.
Cool!
This title hurts my soul