I was thinking about how to get water to arid places, and I realised that you need very fast moving flows to get enough water through a pipe of reasonable gauge to make the enterprise viable. However water is slowed by friction in ordinary pipes, making long distances difficult.

If the friction could be overcome or reduced, it might be possible to better bring water to where it is needed.

The only way I see to move water quickly is to float the water down the tube using some sort of electrostatic or magnetic levitation. However I don't know if this would be possible. The interior of the tube could be at low pressure and the water could move at very high speeds if this could be accomplished.

Perhaps one could harvest the heat energy from the air / solar radiation in arid places and use it to power a propulsion system to compensate for the friction? Like with solar panels or something?

Edit: LOL @ the tags

What about converting the water to a gas (which I'm assuming has less friction) and pumping it that way?

I guess there would have to be something on the other end to effeciently convert it back to a liquid, though.

What about converting the water to a gas (which I'm assuming has less friction) and pumping it that way?

I guess there would have to be something on the other end to effeciently convert it back to a liquid, though.

But it would be a shitload less dense, so you would need a very high volumetric flow rate (read: huge pipe or very fast moving steam) to get much water out the other end.

im sure youd get more answers in DIY.

anyway, why not just use wider pipe? sure it costs more but making a special material that reduces friction would also be really expensive, and any system to propel the water would also be expensive

a large, cylindrical pipe is effective for reducing surface area, which is good

You don't need high velocity flow as much as high volume. I.e. Large pipes. Gravity's useful for the pressure source. Lookit the roman aquaducts.

In abscence of high up sources of water, waterpumps, and water towers.


Srsly. In any case, if I remember correctly, most losses are from turbulent flow in the water.

Is the turbulent flow caused by the water on the outside being slowed by friction? If so then some sort of mixing system is needed, perhaps making the flow rotate would stabilise the stream somewhat?

For water pipe over hundreds, or thousands of miles of miles speeding the water stream up seems the best way to increase utilisation of investment. Would some sort of lubricant work on the inside of the pipe? I think it'd be hard to push water at any speed with it rubbing against solid matter.

Coat the insides with some hydrophobic substance? It might make the water dirty though.

Is the turbulent flow caused by the water on the outside being slowed by friction? If so then some sort of mixing system is needed, perhaps making the flow rotate would stabilise the stream somewhat?

For water pipe over hundreds, or thousands of miles of miles speeding the water stream up seems the best way to increase utilisation of investment. Would some sort of lubricant work on the inside of the pipe? I think it'd be hard to push water at any speed with it rubbing against solid matter.

I think you're missing something here. Water is not a solid. It does not need lubricant, because it is its own lubricant.

Also, friction does not cause losses in pipes. At least not in the way you're thinking. One of the basic tenets of fluid dynamics is that velocity of a fluid at a surface is 0. That is there are no dosses due to friction between a fluid and the pipe wall. However, the pipe wall's roughness causes eddies in the fluid. The rougher the wall, the bigger eddies it creates, and the more loss you have.

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Now, there are two ways to increase flow. One is increasing velocity, the other is increasing diameter. Increasing velocity also increases pressure losses quadratically while increasing flow linearly. Increasing diameter decreases pressure losses linearly (and then some actually) and increases flow quadratically.

Now I'm not saying, that decreasing the frictional losses by using some smoother material wouldn't work, its just that usually the costs associated with doing such are prohibitive for large systems, with the alternative of making bigger pipes.

There are several things to consider when trying to irrigate a distant, area, and these problems can't be condensed to simply, "we need to make water move faster."

So, a big smooth pipe.

I think the biggest issue of irrigating arid regions isn't getting the water there, it's stopping it from GOING anywhere once you get it there! Deserts are deserts for a reason. Any moisture there is going to evaporate in a snap! That's why places like Las Vegas are wasting millions of gallons from the western US's water reservoirs. All the vegas yuppies want to have green lawns, and all the hotels want fountains. Well, guess what: water EVAPORATES when it's hot! And that's why the Colorado River never reaches the sea.

Coat the insides with some hydrophobic substance? It might make the water dirty though.

not necessarily, there are nanotextures that can be made now that are hydrophobic

http://en.wikipedia.org/wiki/Lotus_effect

im actually studying this sort of stuff at university

I think something obvious may be overlooked here. Admittedly, I'm not as up on fluid dynamics as I would like to be, but smooth pipes are ideal, and rough pipes cause eddies that result in friction. If making a pipe smooth enough is too much trouble, why not dimple it to disrupt the eddies? Same basic principle as the dimples in a golf ball, and I know that it's been done for professional swimmers.

I think something obvious may be overlooked here. Admittedly, I'm not as up on fluid dynamics as I would like to be, but smooth pipes are ideal, and rough pipes cause eddies that result in friction. If making a pipe smooth enough is too much trouble, why not dimple it to disrupt the eddies? Same basic principle as the dimples in a golf ball, and I know that it's been done for professional swimmers.

Well, the dimples on a golf ball result in less separation of flow of air directly behind the ball, literally sucking it backward. I believe that the drag on the ball is slightly more due to the dimples, however the pressure drag is much less. Unfortunately I can't see this applying to pipeline. There is no "behind" to speak of when looking at flow past the surface of the pipe, so there's no pressure drag to eliminate.

Maybe for thingks like the regions near joints though. Most pressure loss is through straight pipe, but a properly textured fitting might reduce minor losses in more complex networks of pipes.

You know, I think you're right. I warned you that I was out of my depth (no pun intended).

You know, I think you're right. I warned you that I was out of my depth (no pun intended).

Punnns!!!!

Teflon? It seems to make water bead across the wok instead of spreading.

i think it's hilarious that we still cant duplicate the common veins we all have in our bodies. We have yet to find

ANY thing that doesnt snag/tear blood cells.

i think it's hilarious that we still cant duplicate the common veins we all have in our bodies. We have yet to find

ANY thing that doesnt snag/tear blood cells.

Cholesterol?

i think it's hilarious that we still cant duplicate the common veins we all have in our bodies. We have yet to find

ANY thing that doesnt snag/tear blood cells.

how does dialysis work?

how does dialysis work?

diffusion. synthetic semi permeable membrane