Simulate object being dragged through water / wobbler design

I think this conversation is a bit all over the place because the aim isn’t very clearly defined yet.

With something like CFD simulation of drag on a vehicle or building, you need to simulate the full movement of the fluid with measurable properties and return values for the forces exerted on the parts of the object.

If the thing moving through the fluid is also flexible, then you need to also simulate its solid deformations and the 2 way interaction between the solid and the fluid (and even much professional dedicated CFD software doesn’t include this capability).

If you’re creating a presentation animation of fluid flowing around something where you’re showing the fluid, then you might need to simulate some plausible looking ripples and vortices, but not necessarily in any quantitatively meaningful way that you could engineer from. This sort of plausible looking fluid motion is a big and continuously developing field in its own right, quite separately from engineering CFD.

Finally, if you want to show an animation of how something flaps and moves in a steadily flowing fluid, but not the fluid movement itself, you can often skip simulating the fluid altogether and model it as a constant linear force projected onto area elements, and the movement is surprisingly similar. For something like a flag in the wind, the characteristic flapping motion happens without including anything like turbulence or vortices in the simulation. Part of the flag angled against the wind gets more force applied, causing it to pull other parts of the flag around, and so on, and the waves emerge just from that. (eg Kangaroo Wind Control - #3 by DanielPiker)

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