K2 Engineering

Hi there i am trying to model a rope (cable) floating on the surface of the sea, the rope is constraint on both sides (by a fixed vessel and a winch ashor) the aim is to model the forces of the surface current acting perpendicular to the cable, since this force is depending on the Area the current engages, i think the magnitude of this force depends on the shape of the cable in the water, e.g. a straight line will have lots of current load whereas a line in the direction of the current will have almost none. obviously the shape of the cable will almost follow a horizontal catenary, and therefore not all segments are loaded equally.
how do i model this current force? can anybody suggest anything?
thanks in advance

It sounds like you would need the planar curve equivalent of the Wind goal (which operates on meshes).
I helped Greg with a planar curve pressure goal, which you can see in action here:

I think converting this to a planar curve ‘current’ goal would be easy enough.


i did look at the wind goal, but as you said that needs a mesh and i would like to stay in a 2d world for now (its difficult enough already) :slight_smile:

Here you go - a custom line-current goal
cableCurrent.gh (13.1 KB)

It’s very simple, a cross product with Unit Z to get a vector perpendicular to the line with the same length,
then a dot product to get the projection onto the wind or ‘current’ vector.
Unitize then multiply and we have it.

(Shown here with a bouncy solver just for fun, but generally I recommend using the regular solver)

I’ve always found it neat how complex chaotic flapping behaviour can arise from such simple inputs.

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that is great Daniel, I will have a look and Play
you are the best
if all software would have support like this the world would be a better place

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