algorithmic modeling for Rhino



I am pretty new to gh and kangaroo but I have a feeling there is a description out there to help me calculate the flow paths of liquid on a 3d surface..


I am trying to simulate something like this(see 1:08sec. of video)


Does anyone have any suggestions?

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I tried an experiment with kangaroo which isnt a very scientific way.


1. Make a grid of points.


2. Apply gravity to these points a constant downward vector in kangaroo.


3. Thicken your 3d surface to make it a brep. (a single surface wont work). Set this as a collision object and position it underneath your grid of points.


4. Start the kangaroo animation to drop the points onto the surface (you can mess with bounciness, etc)


You can apply particle trails (a kangaroo utility) to the output particles from kangaroo to make a spline of their path.


You might try subdividing these paths to get points and plug these points into a metaball patch

to get the blobbiness of the example, but others would be able to explain that better.

Hi Lara,


you can also have a look on this discussion.

Benjamin Golder share there a definition doing exactly what you want.

But you need the Grasshopper Python plug-in and also Rhinoceros 3D 5 beta to run this definition.




Thank you very very much!

I will need some time to get my head around these methods and apply them but hopefully, if i can work them, they should be very helpful..


Daniel, do you know if this method would work with a polysurface on rhino?

Lara, if it doesnt work, you can take your polysrf and extrude it downwards and use the thickened version as the collision object. It would be the same with a nurbs surface.

It might also work to constrain particles to a mesh (using PullToMesh). I think this may be a bit faster than using surfaces

Hi Daniel (K.),

I have been trying to set up a definition, according to your instructions but wasn't really successful.

Would you mind having a look at my script to tell me what i am doing wrong?

This was my first kangaroo trial so no judgement please.


Hi Lara,

You were close!

I made a few adjustments to your patch and got it working. You dont need to use the constrain srf component. Also, the collidesrf component is a Kangaroo force, so it needs to plug into the list of forces for Kangaroo instead of geometry. Also the list of forces for Kangaroo always needs to be flattende.

Try this out!



Thank you so much!

The only part i couldn't get to work was recording the trails. For some reason, the trails seem to show null values and the particles don't get recorded. Any guesses why this may be?

Hi Lara,

for me it's working.

Maybe you need to install the latest Kangaroo release if you don't have it already.

And if you are just interested in this fluid path stuff you can also have a look on the SPM Grasshopper plug-in it can do the same.









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