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Editing 40d:Water pressure
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− | + | Dwarf Fortress attempts to replicate [http://en.wikipedia.org/wiki/Fluid_statics#Pressure_in_fluids_at_rest hydrostatic '''water pressure''']. | |
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− | + | There are, however, other mechanisms at work too that try to simulate '''water pressure''', so never think you are on the safe side, especially when trying to trick the game. | |
==Hydrostatic water pressure== | ==Hydrostatic water pressure== | ||
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In layman's terms, if you have a body of water that is higher than an open space below it (such as a tall tower full of water and a hose from it, or a [[lake]] over a mine), and an open route between them, then the water at the lowest [[z-level]] will be 'pressed' by the weight of the water above it. | In layman's terms, if you have a body of water that is higher than an open space below it (such as a tall tower full of water and a hose from it, or a [[lake]] over a mine), and an open route between them, then the water at the lowest [[z-level]] will be 'pressed' by the weight of the water above it. | ||
As a simple model, think of a pipe shaped like a "J". If you pour water in the taller end of the pipe, it will come "up" out of the lower end until the water levels on both sides are equal. If you put your thumb over the lower end and fill the taller end, then release your thumb, the water will move with remarkable speed, and water will continue to come "up" out that lower end until all the water in the taller part is at the same level as the lower part. This is one part of Dwarf Fortress "water pressure" - that if the source is higher, water can come up [[stair]]s, up [[ramp]]s, and over [[channel]], and will continue flowing until it runs out of space or runs out of water above it. | As a simple model, think of a pipe shaped like a "J". If you pour water in the taller end of the pipe, it will come "up" out of the lower end until the water levels on both sides are equal. If you put your thumb over the lower end and fill the taller end, then release your thumb, the water will move with remarkable speed, and water will continue to come "up" out that lower end until all the water in the taller part is at the same level as the lower part. This is one part of Dwarf Fortress "water pressure" - that if the source is higher, water can come up [[stair]]s, up [[ramp]]s, and over [[channel]], and will continue flowing until it runs out of space or runs out of water above it. | ||
− | Note that DF water pressure does not ''exactly'' match natural hydrostatic water pressure - it fills to a [[z-level]] ''one level lower'' than the source. ( | + | Note that DF water pressure does not ''exactly'' match natural hydrostatic water pressure - it fills to a [[z-level]] ''one level lower'' than the source. (As stated by [[Toady]], for reasons of CPU time-saving), the game stops not when all ends of the system are on the same level, but the far levels are one-lower than the source.) |
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Dwarf Fortress does not model surface friction nor air pressure, so the water will not slow in transit nor will 'trapped air bubbles' form. Unless pumped, magma does not have pressure (it cannot flow up, and doesn't appear to move at greater speeds). | Dwarf Fortress does not model surface friction nor air pressure, so the water will not slow in transit nor will 'trapped air bubbles' form. Unless pumped, magma does not have pressure (it cannot flow up, and doesn't appear to move at greater speeds). | ||
− | + | It's also possible for dwarf-built [[pump]]s to pick liquid up and lift it higher, possibly back to the source and thus creating a closed cycle. [[Pump]]s do not create this type of pressure on their own - they do not "push" the liquid that they pump, creating pressure on their own level. They simply lift or pull liquid from one level below them and dump it out at their level, where it will [[flow]] and behave normally on for liquid starting on that level. | |
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− | It's possible for dwarf-built [[pump]]s to pick liquid up and lift it higher, possibly back to the source and thus creating a closed cycle. | ||
== Dangers == | == Dangers == | ||
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== Mitigating dangers == | == Mitigating dangers == | ||
=====Diagonal Flow===== | =====Diagonal Flow===== | ||
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Pressure cannot push water through diagonal gaps between tiles - instead, it will merely flow through if the water level on the other side is low enough. | Pressure cannot push water through diagonal gaps between tiles - instead, it will merely flow through if the water level on the other side is low enough. | ||
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This does not work on a vertical basis - water only travels vertically to a different z-level, never diagonally. | This does not work on a vertical basis - water only travels vertically to a different z-level, never diagonally. | ||
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If you wish to maintain the rate of flow after de-pressurizing, it's recommended that you have more diagonals than water tiles - that is, if the source is 3-tiles wide, you may wish 4 or more diagonal passages. | If you wish to maintain the rate of flow after de-pressurizing, it's recommended that you have more diagonals than water tiles - that is, if the source is 3-tiles wide, you may wish 4 or more diagonal passages. | ||
=====Hatches===== | =====Hatches===== | ||
− | [[Hatch]]es can be placed over [[channel]]s, [[stair]]s, [[ramp]]s etc | + | [[Hatch]]es can be placed over [[channel]]s, [[stair]]s, [[ramp]]s etc to prevent [[water]] moving vertically but still allow the tile to be used, even as a water source (and possibly still for fishing too). |
=====Pumps===== | =====Pumps===== | ||
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↓ ↓↓↓↓↓ # = Normal wall | ↓ ↓↓↓↓↓ # = Normal wall | ||
######<font color="brown">║</font>###<font color="blue">#</font><font color="blue"><b>≈≈≈≈≈</b></font> <font color="blue">#</font> = Wall that pressurised water would flow into if it were to be dug out | ######<font color="brown">║</font>###<font color="blue">#</font><font color="blue"><b>≈≈≈≈≈</b></font> <font color="blue">#</font> = Wall that pressurised water would flow into if it were to be dug out | ||
− | ######<font color="brown">║</font> | + | ######<font color="brown">║</font>###<font color="blue">##</font><font color="blue"><b>≈≈≈≈</b></font> <font color="#2FB6FF">≈</font> = Regular water |
_ ___#<font color="brown">║</font><font color="blue">#######</font><font color="blue"><b>≈≈</b></font> <font color="blue"><b>≈</b></font> = Pressurised water | _ ___#<font color="brown">║</font><font color="blue">#######</font><font color="blue"><b>≈≈</b></font> <font color="blue"><b>≈</b></font> = Pressurised water | ||
#<font color="#2FB6FF">≈≈≈≈≈</font><font color="green"><b>%%</b></font><font color="blue"><b>≈≈≈≈≈≈≈≈</b></font> <font color="green"><b>%%</b></font> = Pump | #<font color="#2FB6FF">≈≈≈≈≈</font><font color="green"><b>%%</b></font><font color="blue"><b>≈≈≈≈≈≈≈≈</b></font> <font color="green"><b>%%</b></font> = Pump | ||
− | + | ######<font color="blue">##</font><font color="blue"><b>≈</b></font><font color="blue">#######</font> <font color="brown">║</font> = Axle | |
− | + | #######<font color="blue">###</font>###### _ = Floor | |
− | Do note that | + | Do note that the screw pump '''will''' create additional water pressure in the destination area, but said pressure will be independent of the source and can be subsequently 'reset' by additional pumps or diagonal gaps. |
== Overall behavior == | == Overall behavior == | ||
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* Have a pump pumping water into a 3-wide tunnel with a 1-wide tunnel below it. Have another pump pumping water into a 1-wide tunnel with a 3-wide tunnel below it. Observe whether the bottom tunnel's water spreads faster in both cases or just in the smaller tunnel. | * Have a pump pumping water into a 3-wide tunnel with a 1-wide tunnel below it. Have another pump pumping water into a 1-wide tunnel with a 3-wide tunnel below it. Observe whether the bottom tunnel's water spreads faster in both cases or just in the smaller tunnel. | ||
* From a pump, fill a cistern which is several levels lower. Shut off the pump and the higher level tiles with hatches once the whole thing is 7/7. Open other hatches above the cistern, combine water with unpressurized water, and see what happens. | * From a pump, fill a cistern which is several levels lower. Shut off the pump and the higher level tiles with hatches once the whole thing is 7/7. Open other hatches above the cistern, combine water with unpressurized water, and see what happens. | ||
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== See Also== | == See Also== | ||
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:* [[water]] | :* [[water]] | ||
:* [[pump]] | :* [[pump]] | ||
− | :* [[ | + | :* [[losing]] |
{{Water FAQ}} | {{Water FAQ}} | ||
− | + | [[Category:Physics]] |