As shown in the picture, I wonder how to achieve this effect on grasshopper.
I don’t want to draw them by manual operation. 
I try my best to use components which I know how to use, however I only can make line type,the whereas the effect in the picture is the curve type…
Here is my files.
Any reply will be appreciated.Thanks.
Random rectangle2.gh (19.5 KB)
Re Hello
I understand well your question, but what you show just a very simple geometry and no curve field at all. For the curve field I have idea, but the geometry type where you want to apply has some influence on the script.
Also if you want to make this, like on you image, it is more simple to make some work on flattened (2D) curves. Booleans are more simple than in 3D.
Whatever for the field there are many tools but I think the one have done on Nautilus are quite useful as they work on mesh.
You will see that there are the field curves and the tool to suppress overlapping curves.
Here I use a mesh with triangular faces. And a field from a Noise. But you could use a field from some guide curves you could draw.
You’ll need Nautilus plugin to use this script. What you’ll get will be less smooth as the tool to draw the flow better is in paid version.
Paid version
The paid version is well worth the small price.
Wow, that impressive. I have learnt a lot.
I seem like a novice compared to you. 
