Kangaroo Wind Control

[zic_23]

Hi guys,

I’m another one new to Kangaroo, trying to create a wavy surface by following youtube videos.
The image shows how far/near I got.

A couple of questions:

1. is there a way to control the frequency and amplitude created by the wind?
2. how may i turn the solver back on after it is converged?

Thanks!
wavy surface_query.gh (9.2 KB)

[diff-arch]

@zic_23

is there a way to control the frequency and amplitude created by the wind?

Not as far as I know, since it only has a directional input, apart from the mesh one.

Check out this thread for more information on wave generation inside Grasshopper:

Ocean Wave Generation in Rhino

For large bodies/deep water, it still isn’t practical to simulate the entire volume as particles, even with any acceleration techniques. If the surface can be treated as a heightfield it can be much more efficient. I found this work really nice: [Water Wave packets] http://visualcomputing.ist.ac.at/publications/2017/WWP/ and here a slightly older simpler approach: [Dispersion Kernels for Water Wave Simulation (SIGGRAPH Asia)] For splashing/breaking waves, heightfields…

@zic_23

how may i turn the solver back on after it is converged?

You can restart the solver by setting its Reset and On inputs to True in this order. For Reset, I’d use a Button component, instead of the Boolean Toggle, since you only want to reset monuntarily.

[DanielPiker]

Hi @zic_23

The flapping of a flag in the wind is not primarily driven by variations in the wind velocity - even in a perfectly steady wind, it will still flap, and that’s what’s happening in the simulation.
What happens is a feedback loop - depending on their angle, some parts of the mesh catch more of the wind, so parts of the mesh move differently. The tension of the fabric makes all the parts interact, and it gets pulled into a new shape, which results in a new wind force distribution, and so on…
This feedback loop can result in periodic oscillations of various frequencies and sometimes chaotic motion.

There isn’t a way to control the oscillation frequency directly - it is the result of complex interaction of multiple factors, including fabric stiffness, wind strength, damping and mesh density.

Even if you did add some controlled variation of the wind strength over time it would not give you any direct control over the oscillation frequency of the flag - it would just be one more variable to adjust in the system.

Here’s a demo

flappingflagdemo.gh (22.5 KB)

[zic_23]

Thank you. That’s very clear. Love this forum.

[zic_23]

thx for the info. i might need to find another way of doing it.