Tugboats Harnessed To Tackle Raging Floodwaters

[shriah]

30 boats are used in Chao Phraya to increase the flow of river 3 times !!

[gregb]

How about this simple test while it's air and not water the test still applies, sit in front of a fan do you feel more air then with it not running? Simple isn't it?

I'd also like to know how much water do these tugs push in 24 hours at maximum throttle? These are rhetorical questions for me by the way designed to make you think before you post more uninformed tripe..

Tugs have massive propellers and huge diesels designed for pushing torque so they push millions of gallons per hour..

Some links for YOUR education..

Tug boats and pulling capacity

Bollard pulling strength

Note that these measurements are stated in "tons of pulling power" and the article does not state what HP nor bollard pulling capacity these tugs have but suffice it to say that any tugs WILL make a difference..

How much water do you think has to be moved to measure tons of power?

Don't know. And is impossible to say without knowing the resistance to flow offered by a river, which in turn empties into the sea. If the sea water has nowhere else to go, then tons of pressure measured over the cross section of the river channel is a tiny, tiny amount.

The problem is essentially the same, whether you are looking at electrical current flow or fluid flow. You have a pressure/voltage source, a current and a resistance. You can say "I'm going to install a 30,000 volt battery inline. That is huge!" However, if your resistance is measured in gigaohms and the current across it in megavolts, it will have almost no effect. Most people find it easier to consider the model in terms of electrical circuits, and if you ignore the details they are equivalent.

As stated above, the optimal place to put these boats is near the mouth of the river and have them push when the sea is at its lowest. At that point, you are only fighting the friction created by water flowing through a channel and the viscosity of the fluid itself. A finite element analysis model would be required to really discover the resistance of the channel to flowing water. Luckily everything tends to be linear at the speeds we are talking about as long as the bulk of the river remains in laminar flow, so it is a fairly simple model for someone with access to the data.

Without access to the data though, it is impossible to know whether several tons are truly helpful or a useless waste of time. The problem as it has been presented to the public is intractable.

It is also important to remember that the boats are only affecting the surface of the river. It may truly be that the surface water is sped up dramatically, but the fluid below is hardly moving. That will eventually cause the flow to dissipate rapidly as the energy of the fast moving water above is transferred to the bulk of the fluid below. So to be honest you would need to take a flow reading at several depths. A boat engine will do nothing for the water at the bottom of the channel, unless you sink the boat.

Here's where we could have used those old German submarines the military wanted to buy.

If you asked me to guess, I suspect this is nothing more than a stunt. Probably by some government official who isn't very smart and wants to impress people that he is doing something. Truthfully, I don't see how it can hurt, but I don't really believe it is going to help either.

[WarpSpeed]

How fast a water flows depends on the outlet. Generating pressure at midpoint would just increase pressure which would dissipiate somewhere down the line and not the end point. As 1 poster mentioned, it would just increase the volume or flood the area downstream but once the engine stops running, the flow will be back the same. Dredging would be a better solution. Multiple dredgers working simultaneously at different point of the river would give a better and long term solution.

Well I was the poster that mentioned the flooding downstream but it's due to the increased volume of water the tugs pump so it DOES increase the water volume and there's no doubt dredging the river would help but then what detrimental effects does that play on the environment? It's been proven that such human engineering and interference has serious effects on the surrounding environment.

[lannarebirth]

How about this simple test while it's air and not water the test still applies, sit in front of a fan do you feel more air then with it not running? Simple isn't it?

I'd also like to know how much water do these tugs push in 24 hours at maximum throttle? These are rhetorical questions for me by the way designed to make you think before you post more uninformed tripe..

Tugs have massive propellers and huge diesels designed for pushing torque so they push millions of gallons per hour..

Some links for YOUR education..

Tug boats and pulling capacity

Bollard pulling strength

Note that these measurements are stated in "tons of pulling power" and the article does not state what HP nor bollard pulling capacity these tugs have but suffice it to say that any tugs WILL make a difference..

How much water do you think has to be moved to measure tons of power?

Don't know. And is impossible to say without knowing the resistance to flow offered by a river, which in turn empties into the sea. If the sea water has nowhere else to go, then tons of pressure measured over the cross section of the river channel is a tiny, tiny amount.

The problem is essentially the same, whether you are looking at electrical current flow or fluid flow. You have a pressure/voltage source, a current and a resistance. You can say "I'm going to install a 30,000 volt battery inline. That is huge!" However, if your resistance is measured in gigaohms and the current across it in megavolts, it will have almost no effect. Most people find it easier to consider the model in terms of electrical circuits, and if you ignore the details they are equivalent.

As stated above, the optimal place to put these boats is near the mouth of the river and have them push when the sea is at its lowest. At that point, you are only fighting the friction created by water flowing through a channel and the viscosity of the fluid itself. A finite element analysis model would be required to really discover the resistance of the channel to flowing water. Luckily everything tends to be linear at the speeds we are talking about as long as the bulk of the river remains in laminar flow, so it is a fairly simple model for someone with access to the data.

Without access to the data though, it is impossible to know whether several tons are truly helpful or a useless waste of time. The problem as it has been presented to the public is intractable.

It is also important to remember that the boats are only affecting the surface of the river. It may truly be that the surface water is sped up dramatically, but the fluid below is hardly moving. That will eventually cause the flow to dissipate rapidly as the energy of the fast moving water above is transferred to the bulk of the fluid below. So to be honest you would need to take a flow reading at several depths. A boat engine will do nothing for the water at the bottom of the channel, unless you sink the boat.

Here's where we could have used those old German submarines the military wanted to buy.

If you asked me to guess, I suspect this is nothing more than a stunt. Probably by some government official who isn't very smart and wants to impress people that he is doing something. Truthfully, I don't see how it can hurt, but I don't really believe it is going to help either.

Actually, the surface water is being slowed by the friction of all those hulls. I'm hoping the artcle was a misprint and it wasn't really 6 boats producing 3200 HP. That amount of HP is less than half of what a single engine in a twin engine tugboat anywhere else would produce. Must be turning awfully tiny screws.

[mistephenso]

There is a video report here that I watched earlier and was wondering whether it was doing any good - even the 'Bangkok Govenor' in the report (Sukhumbhand Paribatra) admits they are still mainly relying on pumping water out to the north of Bangkok...!?

Doesn't look like the ships are shifting much water in the grand scheme of things to me? Better than doing nothing though; especially if it does work!

[WarpSpeed]

How about this simple test while it's air and not water the test still applies, sit in front of a fan do you feel more air then with it not running? Simple isn't it?

I'd also like to know how much water do these tugs push in 24 hours at maximum throttle? These are rhetorical questions for me by the way designed to make you think before you post more uninformed tripe..

Tugs have massive propellers and huge diesels designed for pushing torque so they push millions of gallons per hour..

Some links for YOUR education..

Tug boats and pulling capacity

Bollard pulling strength

Note that these measurements are stated in "tons of pulling power" and the article does not state what HP nor bollard pulling capacity these tugs have but suffice it to say that any tugs WILL make a difference..

How much water do you think has to be moved to measure tons of power?

As stated above, the optimal place to put these boats is near the mouth of the river and have them push when the sea is at its lowest. At that point, you are only fighting the friction created by water flowing through a channel and the viscosity of the fluid itself.

Without access to the data though, it is impossible to know whether several tons are truly helpful or a useless waste of time. The problem as it has been presented to the public is intractable.

It is also important to remember that the boats are only affecting the surface of the river. It may truly be that the surface water is sped up dramatically, but the fluid below is hardly moving. That will eventually cause the flow to dissipate rapidly as the energy of the fast moving water above is transferred to the bulk of the fluid below. So to be honest you would need to take a flow reading at several depths. A boat engine will do nothing for the water at the bottom of the channel, unless you sink the boat.

Here's where we could have used those old German submarines the military wanted to buy.

If you asked me to guess, I suspect this is nothing more than a stunt. Probably by some government official who isn't very smart and wants to impress people that he is doing something. Truthfully, I don't see how it can hurt, but I don't really believe it is going to help either.

The viscosity is irrelevant as the pace of water is increased by the tugs, the reason electrical models just like piping models don't apply is that this water has the ability to overflow it's boundaries down stream making more water downstream regardless of speed of outflow.

Which is the point for those upstream, it is most definitely going to help dry them out quicker regardless of what happens downstream there is no limit to how fast a river can flow and where a river bottle necks for example due to rocky edges the rate and water level increases in height due to a lack of boundaries whether vertical boundaries or horizontal boundaries just as in this case at that point but that has little serious effect on volume passing through that bottle neck.

I.E. Look at floods flowing underneath a bridge where it bottle necks and though the surrounding river may be much lower,wider and slower the water under the bridge is much higher and in many cases right up to the bottom of the bridge (in flood conditions) and rushing very fast with great force. The flow rate has increased due to higher water volume and the water rises to accommodate the bottle neck the bridge creates this is why they also take flood height readings on many bridges as anywhere else is not relevant to the engineered natural flow rate of the river as the bridge is..

While I know you said it tongue in cheek subs wouldn't push as much water as tugs, they're perfect for the job..

As I pointed out previously too the water is not just effected on the surface the entire volume is effected once momentum is achieved and the natural flow direction of water has already provided much of that momentum the tugs are just increasing it at the point of contact which will carry on further then one might expect especially if it's constantly backing up that momentum with more water volume and momentum the longer that occurs the more water volume and momentum will also increase all the way downstream..

If there is no problem with more flooding downstream then it's a viable aid in expediting the removal of flood waters upstream.

[jombom]

If people read the BP article, it is fairly clear somebody is seriously mathematically challenged.

The article says the river is flowing at a rate in the region of 3000 cubic metres per second.

The headline quote says the tugboats are contributing 20% or 57 cubic metres per second.

When I attended school 57 in 3000 was about 2%. A trivial contribution.

Must be the New Math ---- sounds like wonderful stuff.

[taff33]

I can remember a "smart goverment official"saying that the melting of the polar ice caps will not make any difference to Thailands sea level because "we are to far away from them",is it the same person in charge?

[Dag]

If they tethered every soi dog they could catch across the river....facing upstream....their combined leg work could increase the flow tenfold....trademarked, copywrit by Dag.

[kurnell]

A bottle of premium wine for anyone that can find proof that this nonsense has ever worked in the past, and by proof, I ain't talking about a backyard pool

[WarpSpeed]

Guess by that stipulation then nothing scientific will meet your criteria therefore no takers on the wine.. Good thing, not being a wino I see things more clearly then those who are..

So you don't have the capacity to understand the data gained by small scale tests for the purpose of proving theories then as being scientific??

Must be a tefler then as even the space shuttle was tested in small scale water tunnel tests to test it's aero since there was no wind tunnels large enough at the time....

[WarpSpeed]

Better than doing nothing though; especially if it does work!

Well this is the key, most seem to think it's better to just stand there holding there um..... Instead of doing something which WILL have some effect regardless of the tiny minds capacity to understand the hydrodynamics involved..

I find it actually ironically entertaining that those posting here critical of an idea they don't understand calling the Thai's who conceived the idea as being thick... classic!! :cheesy:

[StreetCowboy]

Out of interest, does anyone here actually know what they are talking about?

Has anyone prepared a mental model that they could use to assess the practicality of the solution?

Has anyone done any order-of-magnitude comparisons with other situations?

I don't smoke, so I can't do any fag-packet calculations, but I am sure there are 20-a-day men out there who could throw some more calculated insight on this.

Or are we obliged in the forum rules to make all our decisions by knee-jerk reaction based on prejudice and preconception?

SC

[WarpSpeed]

^ Ermmmm Cowboy I have !! I personally don't need to do the calcs just to prove my position as my more then 25 years experience in hydraulics does that for me.. But most others weeeeeeelll that's another issue ..

Besides if they are incapable of conceptualizing this procedure in the first place based on the concise explanations provided then a bunch of numbers will surely blind them ..

Edited September 22, 2011 by WarpSpeed

[WarpSpeed]

How about this simple test while it's air and not water the test still applies, sit in front of a fan do you feel more air then with it not running? Simple isn't it?

I'd also like to know how much water do these tugs push in 24 hours at maximum throttle? These are rhetorical questions for me by the way designed to make you think before you post more uninformed tripe..

Tugs have massive propellers and huge diesels designed for pushing torque so they push millions of gallons per hour..

Some links for YOUR education..

Tug boats and pulling capacity

Bollard pulling strength

Note that these measurements are stated in "tons of pulling power" and the article does not state what HP nor bollard pulling capacity these tugs have but suffice it to say that any tugs WILL make a difference..

How much water do you think has to be moved to measure tons of power?

Don't know. And is impossible to say without knowing the resistance to flow offered by a river, which in turn empties into the sea. If the sea water has nowhere else to go, then tons of pressure measured over the cross section of the river channel is a tiny, tiny amount.

The problem is essentially the same, whether you are looking at electrical current flow or fluid flow. You have a pressure/voltage source, a current and a resistance. You can say "I'm going to install a 30,000 volt battery inline. That is huge!" However, if your resistance is measured in gigaohms and the current across it in megavolts, it will have almost no effect. Most people find it easier to consider the model in terms of electrical circuits, and if you ignore the details they are equivalent.

As stated above, the optimal place to put these boats is near the mouth of the river and have them push when the sea is at its lowest. At that point, you are only fighting the friction created by water flowing through a channel and the viscosity of the fluid itself. A finite element analysis model would be required to really discover the resistance of the channel to flowing water. Luckily everything tends to be linear at the speeds we are talking about as long as the bulk of the river remains in laminar flow, so it is a fairly simple model for someone with access to the data.

Without access to the data though, it is impossible to know whether several tons are truly helpful or a useless waste of time. The problem as it has been presented to the public is intractable.

It is also important to remember that the boats are only affecting the surface of the river. It may truly be that the surface water is sped up dramatically, but the fluid below is hardly moving. That will eventually cause the flow to dissipate rapidly as the energy of the fast moving water above is transferred to the bulk of the fluid below. So to be honest you would need to take a flow reading at several depths. A boat engine will do nothing for the water at the bottom of the channel, unless you sink the boat.

Here's where we could have used those old German submarines the military wanted to buy.

If you asked me to guess, I suspect this is nothing more than a stunt. Probably by some government official who isn't very smart and wants to impress people that he is doing something. Truthfully, I don't see how it can hurt, but I don't really believe it is going to help either.

Actually, the surface water is being slowed by the friction of all those hulls. I'm hoping the artcle was a misprint and it wasn't really 6 boats producing 3200 HP. That amount of HP is less than half of what a single engine in a twin engine tugboat anywhere else would produce. Must be turning awfully tiny screws.

Pretty sure the report is 6 boats each producing 3200Hp, but you know reporters and their shorthand when making notes.. Actually because the boats are on the surface they produce less flow resistance then any other potential solution.. I also find the straw man argument that just because maybe no one else has tried this approach to be rather small minded as nothing is ever discovered until someone else discovers it but certainly it CAN'T be effective if it was a Thai who implemented it first..

I've also seen they have instituted a really clever way of utilizing plastic road barriers for instant water barriers without having to fill millions of sand bags and also reducing time to implement them it's creative and inspired thinking.. Fewer sand bags required with better capacity and cohesive walled structures which can also be filled with flood water and then eventually easily drained an removed, jing jing..

[StreetCowboy]

^ Ermmmm Cowboy I have !! I personally don't need to do the calcs just to prove my position as my more then 25 years experience in hydraulics does that for me.. But most others weeeeeeelll that's another issue ..

Besides if they are incapable of conceptualizing this procedure in the first place based on the concise explanations provided then a bunch of numbers will surely blind them ..

I can see that if the problem is localised and you are trying to get water over a natural wier (for example, if a bridge is forming a bottleneck) then the impellers might be very effective at forcing more water through that bottleneck. But that relies on being able to dissipate the water downstream.

If the problem is that the whole river gradient is too flat, then you would need to accelerate the whole river length; and if your river is flat and broad, then you have a lot of surface underneath to slow down the flow of water. You might be better to think of it as a hydrostatic problem, rather than a hydrodynamic problem, and think of the impellers as pumping to get a slight head on the downstream side, which would encourage the water to flow away. So you could do a calc to say "if there is 3,000 cubic metres of water flowing per second, what can 6 x 3200 HP (say 14 MW? (Can't check the calc without an envelope to hand) achieve? We could raise all that water

F x S = 14x10^6

(force on 3,000 tonnes water is approx 30x10^6 N)

S = 0.5 ish. So the tug boats would have the same effect as another half metre of rise on the river.

Now is that enough to put the water over the banks? A lot of riparian neighbours would see that as a bad thing.

But I would say, from that calc, that maybe it could work, but the key problem would be what to do with the water downstream. You might, for example, want to add more pumping stations to give another boost to the momentum of the water. Little and often will probably be more efficient and certainly safer than putting all your pressure in one spot.

Anyway, the proof of the pudding is in the eating, so I am sure that if the Thais were interested in educating us, they could tell us how much it helped. THough I am not sure how you would measure that objectively.

SC

SC

[BuckarooBanzai]

I believe the concept will work but at an extremely low efficiency. The boats will indeed pump the water downstream in the immediate area of the propellers. This will create a bulge of water on the downstream side. So if we imagine a dome of water and how it reacts it is a lot like dropping a water balloon and it sploshes out in a 360 degree release of energy.

Much of the water will attempt to escape to the low pressure area created by the boat pumps up river from the boats by avoiding the area of the pumping propellers. This drastically reduces the efficiency.

But since their is a dome created on the downstream side there will be a percentage of the dome that tries to escape downriver as well thus increasing volume above the normal flow.

The only way for it to work as in the minds of the genies thinking this up is to seal all areas of the river where the reverse flow towards the low pressure upstream can take place and which would result in a more conventional pump like scenario.

This also assumes that with the increased plugging up and constriction of the flow area around the boat pumps the props could keep up and surpass the normal flow volume of the river.

It would be fun to watch though!

[WarpSpeed]

^ Ermmmm Cowboy I have !! I personally don't need to do the calcs just to prove my position as my more then 25 years experience in hydraulics does that for me.. But most others weeeeeeelll that's another issue ..

Besides if they are incapable of conceptualizing this procedure in the first place based on the concise explanations provided then a bunch of numbers will surely blind them ..

I can see that if the problem is localised and you are trying to get water over a natural wier (for example, if a bridge is forming a bottleneck) then the impellers might be very effective at forcing more water through that bottleneck. But that relies on being able to dissipate the water downstream.

If the problem is that the whole river gradient is too flat, then you would need to accelerate the whole river length; and if your river is flat and broad, then you have a lot of surface underneath to slow down the flow of water. You might be better to think of it as a hydrostatic problem, rather than a hydrodynamic problem, and think of the impellers as pumping to get a slight head on the downstream side, which would encourage the water to flow away. So you could do a calc to say "if there is 3,000 cubic metres of water flowing per second, what can 6 x 3200 HP (say 14 MW? (Can't check the calc without an envelope to hand) achieve? We could raise all that water

F x S = 14x10^6

(force on 3,000 tonnes water is approx 30x10^6 N)

S = 0.5 ish. So the tug boats would have the same effect as another half metre of rise on the river.

Now is that enough to put the water over the banks? A lot of riparian neighbours would see that as a bad thing.

But I would say, from that calc, that maybe it could work, but the key problem would be what to do with the water downstream. You might, for example, want to add more pumping stations to give another boost to the momentum of the water. Little and often will probably be more efficient and certainly safer than putting all your pressure in one spot.

Anyway, the proof of the pudding is in the eating, so I am sure that if the Thais were interested in educating us, they could tell us how much it helped. THough I am not sure how you would measure that objectively.

SC

SC

Yes as I mentioned earlier the optimum place to locate another set of tugs would be just upstream prior to the rivers mouth to complete the process.. Still I'm sure it is going to have some detrimental effect in terms of more local flooding downstream let's not forget as the flooding moves southward anyways it is already flooding the river banks so it's a virtual certainty that it will cause more flooding downstream.

The Dutch, which have been mentioned as flood experts and rightly so do this very thing understanding that there is no way to completely control the floods they face, they have designated neighborhoods they've prepared in advance for flooding that are sacrificial over the greater whole..

I always find it funny that in an attempt to use an elementary example like the swimming pool because the more complicated ones are sure to escape anyone who can't follow the simple example and it still gets glossed over and discounted .

Edited September 22, 2011 by WarpSpeed

[WarpSpeed]

I believe the concept will work but at an extremely low efficiency. The boats will indeed pump the water downstream in the immediate area of the propellers. This will create a bulge of water on the downstream side. So if we imagine a dome of water and how it reacts it is a lot like dropping a water balloon and it sploshes out in a 360 degree release of energy.

Much of the water will attempt to escape to the low pressure area created by the boat pumps up river from the boats by avoiding the area of the pumping propellers. This drastically reduces the efficiency.

But since their is a dome created on the downstream side there will be a percentage of the dome that tries to escape downriver as well thus increasing volume above the normal flow.

The only way for it to work as in the minds of the genies thinking this up is to seal all areas of the river where the reverse flow towards the low pressure upstream can take place and which would result in a more conventional pump like scenario.

This also assumes that with the increased plugging up and constriction of the flow area around the boat pumps the props could keep up and surpass the normal flow volume of the river.

It would be fun to watch though!

There's some truth to what you say Buckaroo but the natural and now increased flow of the river eliminates much of the low pressure zones to which you speak, so the loss of efficiency is not so great.. If it were still, stagnant water you'd be absolutely correct but it would still be better then standing idly by and waiting for hot sun and mother nature especially when rain clouds are still overhead..

Edited September 22, 2011 by WarpSpeed

[Mirth]

Don't mean to argue but the CP river ain't exactly environmentally friendly. Considering the amount of waste dumped into the river on a daily basis, multiply it by a century, dredging would be the solution cos it would be removing all the muck that have accumulated on the river bed, allowing marine life to once again flourish and at the same time make the river deeper thus solving the flood problem.

Only factor no one is doing that is cos of the cost. Eventually someone will and that person is going to be a rich person.

Well I was the poster that mentioned the flooding downstream but it's due to the increased volume of water the tugs pump so it DOES increase the water volume and there's no doubt dredging the river would help but then what detrimental effects does that play on the environment? It's been proven that such human engineering and interference has serious effects on the surrounding environment.

[WarpSpeed]

Don't mean to argue but the CP river ain't exactly environmentally friendly. Considering the amount of waste dumped into the river on a daily basis, multiply it by a century, dredging would be the solution cos it would be removing all the muck that have accumulated on the river bed, allowing marine life to once again flourish and at the same time make the river deeper thus solving the flood problem.

Only factor no one is doing that is cos of the cost. Eventually someone will and that person is going to be a rich person.

Well I was the poster that mentioned the flooding downstream but it's due to the increased volume of water the tugs pump so it DOES increase the water volume and there's no doubt dredging the river would help but then what detrimental effects does that play on the environment? It's been proven that such human engineering and interference has serious effects on the surrounding environment.

Well that's precisely the problem innit? The toxic crap that comes up from the bottom.. Dredging is also not an immediate fix it's more a long term aid but ain't going to happen over night no matter where it is but TIT where it took them 40 years post planning to finally complete Swampy .

[BuckarooBanzai]

I believe the concept will work but at an extremely low efficiency. The boats will indeed pump the water downstream in the immediate area of the propellers. This will create a bulge of water on the downstream side. So if we imagine a dome of water and how it reacts it is a lot like dropping a water balloon and it sploshes out in a 360 degree release of energy.

Much of the water will attempt to escape to the low pressure area created by the boat pumps up river from the boats by avoiding the area of the pumping propellers. This drastically reduces the efficiency.

But since their is a dome created on the downstream side there will be a percentage of the dome that tries to escape downriver as well thus increasing volume above the normal flow.

The only way for it to work as in the minds of the genies thinking this up is to seal all areas of the river where the reverse flow towards the low pressure upstream can take place and which would result in a more conventional pump like scenario.

This also assumes that with the increased plugging up and constriction of the flow area around the boat pumps the props could keep up and surpass the normal flow volume of the river.

It would be fun to watch though!

There's some truth to what you say Buckaroo but the natural and now increased flow of the river eliminates much of the low pressure zones to which you speak, so the loss of efficiency is not so great.. If it were still, stagnant water you'd be absolutely correct but it would still be better then standing idly by and waiting for hot sun and mother nature especially when rain clouds are still overhead..

When you add energy by pumping with the engines of the boats you exceed the energy levels of the natural flow to which you refer. This creates a trough and a bulge. The addition of energy exceeds the natural flow of the river as you describe it and does lead to an imbalance of the local system. Water is a master of seeking the path of least resistance and if there is a low pressure area it will chase it faster than a soi dog chasing a female bitch in heat. Sorry for the play on words but the reality is every bit as intense. Cheers.

[WarpSpeed]

I believe the concept will work but at an extremely low efficiency. The boats will indeed pump the water downstream in the immediate area of the propellers. This will create a bulge of water on the downstream side. So if we imagine a dome of water and how it reacts it is a lot like dropping a water balloon and it sploshes out in a 360 degree release of energy.

Much of the water will attempt to escape to the low pressure area created by the boat pumps up river from the boats by avoiding the area of the pumping propellers. This drastically reduces the efficiency.

But since their is a dome created on the downstream side there will be a percentage of the dome that tries to escape downriver as well thus increasing volume above the normal flow.

The only way for it to work as in the minds of the genies thinking this up is to seal all areas of the river where the reverse flow towards the low pressure upstream can take place and which would result in a more conventional pump like scenario.

This also assumes that with the increased plugging up and constriction of the flow area around the boat pumps the props could keep up and surpass the normal flow volume of the river.

It would be fun to watch though!

There's some truth to what you say Buckaroo but the natural and now increased flow of the river eliminates much of the low pressure zones to which you speak, so the loss of efficiency is not so great.. If it were still, stagnant water you'd be absolutely correct but it would still be better then standing idly by and waiting for hot sun and mother nature especially when rain clouds are still overhead..

When you add energy by pumping with the engines of the boats you exceed the energy levels of the natural flow to which you refer. This creates a trough and a bulge. The addition of energy exceeds the natural flow of the river as you describe it and does lead to an imbalance of the local system. Water is a master of seeking the path of least resistance and if there is a low pressure area it will chase it faster than a soi dog chasing a female bitch in heat. Sorry for the play on words but the reality is every bit as intense. Cheers.

No argument which is why I said some truth in what you said, but it is not nearly as much a factor in impeding efficiency though as say a stagnant body of water would be..

[BuckarooBanzai]

I believe the concept will work but at an extremely low efficiency. The boats will indeed pump the water downstream in the immediate area of the propellers. This will create a bulge of water on the downstream side. So if we imagine a dome of water and how it reacts it is a lot like dropping a water balloon and it sploshes out in a 360 degree release of energy.

Much of the water will attempt to escape to the low pressure area created by the boat pumps up river from the boats by avoiding the area of the pumping propellers. This drastically reduces the efficiency.

But since their is a dome created on the downstream side there will be a percentage of the dome that tries to escape downriver as well thus increasing volume above the normal flow.

The only way for it to work as in the minds of the genies thinking this up is to seal all areas of the river where the reverse flow towards the low pressure upstream can take place and which would result in a more conventional pump like scenario.

This also assumes that with the increased plugging up and constriction of the flow area around the boat pumps the props could keep up and surpass the normal flow volume of the river.

It would be fun to watch though!

There's some truth to what you say Buckaroo but the natural and now increased flow of the river eliminates much of the low pressure zones to which you speak, so the loss of efficiency is not so great.. If it were still, stagnant water you'd be absolutely correct but it would still be better then standing idly by and waiting for hot sun and mother nature especially when rain clouds are still overhead..

When you add energy by pumping with the engines of the boats you exceed the energy levels of the natural flow to which you refer. This creates a trough and a bulge. The addition of energy exceeds the natural flow of the river as you describe it and does lead to an imbalance of the local system. Water is a master of seeking the path of least resistance and if there is a low pressure area it will chase it faster than a soi dog chasing a female bitch in heat. Sorry for the play on words but the reality is every bit as intense. Cheers.

No argument which is why I said some truth in what you said, but it is not nearly as much a factor in impeding efficiency though as say a stagnant body of water would be..

You are IMHO absolutely correct. There have been suggestions of dredging the river but if the flow is constricted anywhere that is a waste of time as various places become stagnant. This helps no one but still costs a lot of baht.

The reality you have arrived at is that there is no short term solution to flooding. If you want to control flooding maybe take a hint from Malaysia who has actually invested in flood control. Verbiage does not control floods. Smart investments do. Cheers to you WarpSpeed.

[WarpSpeed]

^ Yes Malaysia has quite some elaborate flood control system design and was veeery expensive and complicated to build with multi-functionality serving as a vehicle tunnel when it's not moving water through the city, top stuff..

[gregb]

I will happily take on physics with anyone here. Since nobody has done a finite element analysis of the river, nobody has any idea of what the actual effect might be in reality. But let's take a hypothetical example and try to determine what the MAXIMUM effect might be. This is a river with in a channel with zero friction, and where 100% of the energy of the engine was transferred to the water.

How much could the water actually be sped up? Well, let's simply do some high school physics:

KE = 1/2*m*v^2, where m is the mass of the water in kg we are acting upon, and v is the speed in meters/sec.

We know that 1 hp-hr is equal to 2.686 * 10^6 joules, so 1 hp-second = 746 joules.

We will use the variable HP to refer to the aggregate horsepower from all the boat engines.

Now, let's do math we all learned when we were 10.

First, we need to know m, the mass of the water we are acting on. According to Wikipedia, the Choa Phraya river flow is between 718 m^3/second on average, and 5960 m^3/sec at maximum, which is 5.96*10^6 kg/sec. Since we are worried about the river overflowing its banks, we can pretty much assume we are at maximum naturally.

So, m is equal to the flow rate * t. This is perfect because we can already see the t's will cancel, just as they should.

So let's ask a 10 year old to help us out:

1/2*m*v^2 = 746*HP*t

1/2*FR*t*v^2 = 746*HP*t

Cancel the t's, and we get:

1/2*FR*v^2 = 746*HP

or v = sqrt(2*746*HP/FR)

Remember, this is a theoretical maximum we could never actually hope to achieve. In reality, we'd be lucky to get 20% of the energy transferred to the water. Most of it will be lost as heat to the environment. So what can we expect as a delta v?

v = sqrt((2*746/5.96 *10^6)*HP) = 15.8 * 10^-3 * sqrt(HP)

If the media ever reports a delta_v greater than this, then we know somebody is lying, because we could only get this number in a perfect world by ignoring all the realities of thermodynamics.

So what was that published figure? 30 boats? And someone said about 3200 HP per boat? OK, what could that give us for a delta v in a world where we could ignore friction?

v = 15.8 * 10^-3 * sqrt(30*3200) = 4.9 m/s

5 m/s is a pretty respectable number, but remember how many realities of physics we had to ignore to get this. The likely reality is we would be looking at adding approximately 1 m/s at best to the river from pushing with 96,000 HP.

So how much is 1 m/s?

As a percentage of the existing flow rate, it would be most noticeable in an area with the largest cross section and therefore the slowest current. Obviously we don't have this information for the exact location where the boats were located, but some Google searching gives a typical example of approximately 0.2 - 0.4 m/s nominal rate at the mouth of the river. We could expect this to be higher further upstream where the channel is smaller, but our very simple grade school analysis does seem to indicate that the idea should not be dismissed out of hand.

I am forced to conclude that it does appear to be within the realm of physics as we understand it for 30 boats of 3200 HP to have increased the flow of the river to 3 times its normal speed. Again, this doesn't say anything about where all that water will go, but it would seem that the reports of what they have achieved are not entirely unreasonable. I also tend to suspect however that the number 300% is somewhat exaggerated. Engineers are not above being less than thorough when making measurements if they have an emotional involvement in the outcome.

On the whole I'd have to give the Thai engineers credit. My initial bias was that I thought the numbers would say they were smoking some really good weed, but I came away from this realizing that the method is not necessarily without merit.

[StreetCowboy]

I will happily take on physics with anyone here. Since nobody has done a finite element analysis of the river, nobody has any idea of what the actual effect might be in reality. But let's take a hypothetical example and try to determine what the MAXIMUM effect might be. This is a river with in a channel with zero friction, and where 100% of the energy of the engine was transferred to the water.

How much could the water actually be sped up? Well, let's simply do some high school physics:

KE = 1/2*m*v^2, where m is the mass of the water in kg we are acting upon, and v is the speed in meters/sec.

We know that 1 hp-hr is equal to 2.686 * 10^6 joules, so 1 hp-second = 746 joules.

We will use the variable HP to refer to the aggregate horsepower from all the boat engines.

Now, let's do math we all learned when we were 10.

First, we need to know m, the mass of the water we are acting on. According to Wikipedia, the Choa Phraya river flow is between 718 m^3/second on average, and 5960 m^3/sec at maximum, which is 5.96*10^6 kg/sec. Since we are worried about the river overflowing its banks, we can pretty much assume we are at maximum naturally.

So, m is equal to the flow rate * t. This is perfect because we can already see the t's will cancel, just as they should.

So let's ask a 10 year old to help us out:

1/2*m*v^2 = 746*HP*t

1/2*FR*t*v^2 = 746*HP*t

Cancel the t's, and we get:

1/2*FR*v^2 = 746*HP

or v = sqrt(2*746*HP/FR)

Remember, this is a theoretical maximum we could never actually hope to achieve. In reality, we'd be lucky to get 20% of the energy transferred to the water. Most of it will be lost as heat to the environment. So what can we expect as a delta v?

v = sqrt((2*746/5.96 *10^6)*HP) = 15.8 * 10^-3 * sqrt(HP)

If the media ever reports a delta_v greater than this, then we know somebody is lying, because we could only get this number in a perfect world by ignoring all the realities of thermodynamics.

So what was that published figure? 30 boats? And someone said about 3200 HP per boat? OK, what could that give us for a delta v in a world where we could ignore friction?

v = 15.8 * 10^-3 * sqrt(30*3200) = 4.9 m/s

5 m/s is a pretty respectable number, but remember how many realities of physics we had to ignore to get this. The likely reality is we would be looking at adding approximately 1 m/s at best to the river from pushing with 96,000 HP.

So how much is 1 m/s?

As a percentage of the existing flow rate, it would be most noticeable in an area with the largest cross section and therefore the slowest current. Obviously we don't have this information for the exact location where the boats were located, but some Google searching gives a typical example of approximately 0.2 - 0.4 m/s nominal rate at the mouth of the river. We could expect this to be higher further upstream where the channel is smaller, but our very simple grade school analysis does seem to indicate that the idea should not be dismissed out of hand.

I am forced to conclude that it does appear to be within the realm of physics as we understand it for 30 boats of 3200 HP to have increased the flow of the river to 3 times its normal speed. Again, this doesn't say anything about where all that water will go, but it would seem that the reports of what they have achieved are not entirely unreasonable. I also tend to suspect however that the number 300% is somewhat exaggerated. Engineers are not above being less than thorough when making measurements if they have an emotional involvement in the outcome.

On the whole I'd have to give the Thai engineers credit. My initial bias was that I thought the numbers would say they were smoking some really good weed, but I came away from this realizing that the method is not necessarily without merit.

Or you could refer to my previous calculation, which indicated that the tugs could hope to generate the same benefit as an extra half metre of drop on the river, which I think (based on superficial impression and unfounded opinion) is significantly less than your estimate, but I don't have the time to hand to reconcile the apparent difference.

SC

[BuckarooBanzai]

I will happily take on physics with anyone here. Since nobody has done a finite element analysis of the river, nobody has any idea of what the actual effect might be in reality. But let's take a hypothetical example and try to determine what the MAXIMUM effect might be. This is a river with in a channel with zero friction, and where 100% of the energy of the engine was transferred to the water.

Any one with a degree of understanding of physics will tell you that your logic is faulty. You made one very true statement "nobody has any idea of what the actual effect might be in reality" and then you went ballistic. Capture the real environment and then use your physics. Try again please.

I stand by my first statement "it works but at very low efficiencies.

[gregb]

I will happily take on physics with anyone here. Since nobody has done a finite element analysis of the river, nobody has any idea of what the actual effect might be in reality. But let's take a hypothetical example and try to determine what the MAXIMUM effect might be. This is a river with in a channel with zero friction, and where 100% of the energy of the engine was transferred to the water.

Any one with a degree of understanding of physics will tell you that your logic is faulty. You made one very true statement "nobody has any idea of what the actual effect might be in reality" and then you went ballistic. Capture the real environment and then use your physics. Try again please.

I stand by my first statement "it works but at very low efficiencies.

OK...I'm happy to hear more about where my logic is faulty. I agree conservation of energy is not necessarily the most enlightening approach to the problem, but it could very easily have determined if the idea was a complete work of fiction.

As it is, my analysis implies that it may be possible. I originally shared your opinion that it sounded ridiculous, but I was specifically trying to decide if the announced statement, namely that they had increased the flow of the river 300% with 30 boats, was theoretically possible. Theoretically it seems it might be.

If we had more data, we could make a more detailed analysis. Since neither you nor I have that data, we can't. It is really as simple as that.

But I can find no obvious reason to discount the claims that the boats increased the flow of the river by the amount they claimed. If you can, please be my guest. Unlike many I am genuinely interested in whether or not this can work, and more importantly why or why not that is the case. I started out being completely dismissive of the idea as ludicrous, but having seen that it can't be ruled out by simple arguments, I now find myself wondering what the real answer is.

So please enlighten me. As I said...I will put my ability to understand physics up against anyone. Nothing intimidates me. Give it your best shot with real numbers. What exactly is the low efficiency you claim, and how did you arrive at your answer?

BTW, I hardly call applying a simple energy equivalence calculation as "going ballistic". Such simple analysis has allowed me in countless previous situations to immediately recognize someone who was full of fecal matter. It is a simple skill that everyone should learn.

[BuckarooBanzai]

I will happily take on physics with anyone here. Since nobody has done a finite element analysis of the river, nobody has any idea of what the actual effect might be in reality. But let's take a hypothetical example and try to determine what the MAXIMUM effect might be. This is a river with in a channel with zero friction, and where 100% of the energy of the engine was transferred to the water.

Any one with a degree of understanding of physics will tell you that your logic is faulty. You made one very true statement "nobody has any idea of what the actual effect might be in reality" and then you went ballistic. Capture the real environment and then use your physics. Try again please.

I stand by my first statement "it works but at very low efficiencies.

OK...I'm happy to hear more about where my logic is faulty. I agree conservation of energy is not necessarily the most enlightening approach to the problem, but it could very easily have determined if the idea was a complete work of fiction.

As it is, my analysis implies that it may be possible. I originally shared your opinion that it sounded ridiculous, but I was specifically trying to decide if the announced statement, namely that they had increased the flow of the river 300% with 30 boats, was theoretically possible. Theoretically it seems it might be.

If we had more data, we could make a more detailed analysis. Since neither you nor I have that data, we can't. It is really as simple as that.

But I can find no obvious reason to discount the claims that the boats increased the flow of the river by the amount they claimed. If you can, please be my guest. Unlike many I am genuinely interested in whether or not this can work, and more importantly why or why not that is the case. I started out being completely dismissive of the idea as ludicrous, but having seen that it can't be ruled out by simple arguments, I now find myself wondering what the real answer is.

So please enlighten me. As I said...I will put my ability to understand physics up against anyone. Nothing intimidates me. Give it your best shot with real numbers. What exactly is the low efficiency you claim, and how did you arrive at your answer?

BTW, I hardly call applying a simple energy equivalence calculation as "going ballistic". Such simple analysis has allowed me in countless previous situations to immediately recognize someone who was full of fecal matter. It is a simple skill that everyone should learn.

You are indeed a good person. You are using your intellect to try and help. And I am indeed full of fecal matter as are we all. So no offense taken.

The truth is that water takes the easiest way to relax the local energy system. It flows from high pressure to low pressure.

If low pressure is up stream than than that is where it will go.

God bless us one and all!

Edit - We really can not argue about this Thai plan can we?

Edited September 23, 2011 by BuckarooBanzai