Flowmap direction

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Hi there,

For a school project I am working on a river. I am getting very nice results with the standard flowmap tools already, but I wanted to change some things.

First of all, I wanted the river to flow quicker where it is narrow, because velocity = flowrate/area. This does work. Note that to make this work, I went into the flowmap to color node and got rid of the normalize, because I want values over 1 for the speed.
Then I also wanted the water to flow quicker, so I thought I'll just take v.y and multiply it with 9.81. This seems to work at first hand, but then at the top of the slopes of my river, the water seems to flow in the opposite direction (back up). I am not entirely sure why this happens. When I set the gravity to a lower value, like 3, this doesn't really happen yet (or at least not visible).

Can anyone explain to me why this is happening? Also, is there a better way of achieving this result, rather than just not normalizing any of the vectors?

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would be easier if you could post your hip file.

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Hi,

very rough ideas based on your example:

if you construct the surface by a curve you can use a width attribute along the curve, which determines the local width of the river. This attribute can be used to control the speed.

Another attribute can be the curve's derivative (call it D, which is a vector). the y-component of this derivative determines the gradient, which should also influence the speed. Use something like abs(D.y) / length(D) to get the relative amount to be multiplied with the maximum force.

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Yes, I have indeed constructed my river based on a curve that I gave a width attribute. I will have a look into this derivative! Sounds like it could be just what I need  I will also still upload my hip file later, since I can't get to it right now. Thanks!

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Here is the file!

River_flowrate_v2.hiplc

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