The bottom of the river is at the bottom of level -1, the top of the river is at the top of level -1 so yes, it will flood that level if you allow it to, the pressure will push it up despite your U bend. This is why I dont open up the top of a well until the cistern is full and I have closed the floodgate to prevent more comming in and pushing it up when I channel the wells out. However, you can have the cistern at level -1 and the well at level 0 without worrying about that as the water level will not rise above the rivers level.But my point was that "Diagram A" on the wiki page I linked to shows the water on the right of the u-bend only filling up to one level below the level of the undammed river. Is the wiki article wrong? It seems that pressure is causing it to fill up to the same level as the undammed river.
But my point was that "Diagram A" on the wiki page I linked to shows the water on the right of the u-bend only filling up to one level below the level of the undammed river. Is the wiki article wrong? It seems that pressure is causing it to fill up to the same level as the undammed river.
I agree. Honestly I don't know why it should make any difference. The river is going to be filled to a constant level because of the flow of water. And water in a U bend (in real life) fills to equal levels on each side, so it should fill up to the source of the river.
But my point was that "Diagram A" on the wiki page I linked to shows the water on the right of the u-bend only filling up to one level below the level of the undammed river. Is the wiki article wrong? It seems that pressure is causing it to fill up to the same level as the undammed river.
I would treat any river as diagram B.
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Erm, how would that work? Water can't travel diagionally on the z axis.I agree. Honestly I don't know why it should make any difference. The river is going to be filled to a constant level because of the flow of water. And water in a U bend (in real life) fills to equal levels on each side, so it should fill up to the source of the river.
But my point was that "Diagram A" on the wiki page I linked to shows the water on the right of the u-bend only filling up to one level below the level of the undammed river. Is the wiki article wrong? It seems that pressure is causing it to fill up to the same level as the undammed river.
I would treat any river as diagram B.
My bet is that whoever did that science mined from the river at a diagonal.Code: [Select]#~~~###Rather than
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I always place a diagonal at the top level I want to fill, that is a full proof way of avoiding floods. I would also advise always placing a floodgate/block in the inlet before you connect to the water source. This functions both as an emergency stop and can be useful if you need to work on the plumbing later...Yep I definitely agree on the "diagonal on the top level you want to fill" rule. Only trouble is, diagonals also slow the speed of the water down quite a bit so I guess for a significantly quick fill you'll want several channels that combine, all of which have dialogals on them.
I always place a diagonal at the top level I want to fill, that is a full proof way of avoiding floods. I would also advise always placing a floodgate/block in the inlet before you connect to the water source. This functions both as an emergency stop and can be useful if you need to work on the plumbing later...Yep I definitely agree on the "diagonal on the top level you want to fill" rule. Only trouble is, diagonals also slow the speed of the water down quite a bit so I guess for a significantly quick fill you'll want several channels that combine, all of which have dialogals on them.
Any way if this wiki article is wrong it should probably be changed.
Another question: does water's falling actually create pressure? From my experiments, it seems to. So even if you eliminate the pressure on level -1 with a diagonal, if the water falls down to level -2 and then level -3, it will rise up through any holes to level -2 again presumably because of the pressure generated by its falling down from -1 to -2. This may only apply if the water is taken from some flowing water, I'm not sure.
Another question: does water's falling actually create pressure? From my experiments, it seems to. So even if you eliminate the pressure on level -1 with a diagonal, if the water falls down to level -2 and then level -3, it will rise up through any holes to level -2 again presumably because of the pressure generated by its falling down from -1 to -2. This may only apply if the water is taken from some flowing water, I'm not sure.
But if you have a diagonal on -1 (BEFORE the water falls to the next level), you've removed pressure, right? So, from then on, the water shouldn't be able to go "up" any levels, should it? I thought only pressure could make water go "up".Another question: does water's falling actually create pressure? From my experiments, it seems to. So even if you eliminate the pressure on level -1 with a diagonal, if the water falls down to level -2 and then level -3, it will rise up through any holes to level -2 again presumably because of the pressure generated by its falling down from -1 to -2. This may only apply if the water is taken from some flowing water, I'm not sure.
This isn't really 'falling'. You're merely filling a u-shaped container from the top. It falls when the container is empty, but the z bend on -1 ensures that the water will fill up to that level always.
But if you have a diagonal on -1 (BEFORE the water falls to the next level), you've removed pressure, right? So, from then on, the water shouldn't be able to go "up" any levels, should it? I thought only pressure could make water go "up".
Here are the pictures!Could you post these with the Ironhand tileset for those of us whose ASCII comprehension is mediocre at best? :)
Jez9999, did you stop the river from flowing off the map?Come to think of it, on my test map the river empties out into the ocean. Perhaps that behaves similarly to a dammed river?
Jez9999, did you stop the river from flowing off the map?Come to think of it, on my test map the river empties out into the ocean. Perhaps that behaves similarly to a dammed river?
To me it seems that the DF-physics are closer to reality than we all thought. It seems, that if the distance between the flowing tiles and the channel is large enough, the dynamic-pressure-behavior disapers as it would in real life. it only accounts for static pressure while the total pressure remains the same.Huh??
To me it seems that the DF-physics are closer to reality than we all thought. It seems, that if the distance between the flowing tiles and the channel is large enough, the dynamic-pressure-behavior disapers as it would in real life. it only accounts for static pressure while the total pressure remains the same.
To me it seems that the DF-physics are closer to reality than we all thought. It seems, that if the distance between the flowing tiles and the channel is large enough, the dynamic-pressure-behavior disapers as it would in real life. it only accounts for static pressure while the total pressure remains the same.
DF ONLY accounts for static pressure. Dynamic pressure isn't simulated.
To me it seems that the DF-physics are closer to reality than we all thought. It seems, that if the distance between the flowing tiles and the channel is large enough, the dynamic-pressure-behavior disapers as it would in real life. it only accounts for static pressure while the total pressure remains the same.
DF ONLY accounts for static pressure. Dynamic pressure isn't simulated.
by the looks of the spoilers above DF simulates the dynamic pressure as a form of horizontal static pressure - otherwise there wouldn't be a difference between the damned an the flowing river!
OK I updated the wiki article (http://dwarffortresswiki.org/index.php/DF2012:Pressure#Water_in_a_U-Bend) to indicate that flowing into the sea actually counts as a dammed river.
I still have one more question, to all you experts out there. :) In diagram A of that article, it shows that the undammed river tiles to the left do not exert pressure because they are flowing. It then shows the one river tile to the right exerting a downward pressure to the tile below it. My question is, why does it exert this downward pressure? If this tile is flowing too, then wouldn't it fail to exert downward pressure, like the other flowing river tiles? Obviously this diagram is correct as experiments have shown, but does anyone have an idea as to why, given the game mechanics?
To me it seems that the DF-physics are closer to reality than we all thought. It seems, that if the distance between the flowing tiles and the channel is large enough, the dynamic-pressure-behavior disapers as it would in real life. it only accounts for static pressure while the total pressure remains the same.
DF ONLY accounts for static pressure. Dynamic pressure isn't simulated.
by the looks of the spoilers above DF simulates the dynamic pressure as a form of horizontal static pressure - otherwise there wouldn't be a difference between the damned an the flowing river!
The dynamic part of pressure is proportional to fluid velocity. In RL the total pressure of a flowing river is HIGHER than a damned river. So the DF effect that water rises further when tapped to a damned river has nothing to do with reality.
I agree what's described in Diagram A in the wiki is a bit odd. I can find no correlation to real effects, so I'm assuming a programming artefact. (Namely fluid simulation, when having to choose if to put a tile of water at the end of a u-bend or on the outflow of the river, always opts for the outflow.)
If you can name a fluid dynamics effect that would explain the strange behaviour in Diagram A, I will listen. I can say dynamic pressure is not it.
Back to the original problem: In the first post of jez9999 the question was (I hope I got that right) why the tunnel on the inside end of the u-bend is being flooded, since the water is being taken out of the a flowing river, and on the same z-level as the bottom of the river (therefore the flowing water). The wiki says, that the water shouldn't do so (diagram A). To me this behaviour makes sense (see first paragraph). I believe the flood is happening because DF is able to notice tiles that are not in flowing direction are not accounted as being part of the flow system (maybe flow has something like a pathing-algorithm noticing dead ends). Therefore the dynamic pressure behaviour stated above does not apply to them.DF has no concept of flow-path. See the section on flowing-water http://dwarffortresswiki.org/index.php/Waterwheel