# Simple volume flow solver (just divergence previous and current frame)

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Posted (edited)

Please, is there a simple solution to compare previous and current frame of volume moving around deforming geometry?

I mean just "air", just compute velocity vector volume "everywhere" around the deforming object in a container.
I dont need turbulence or inertia/momentum/mass of the fluid.
I could use flip solver and extract velocities, but I hope there could be something simpler and computationally faster?

Edited by ikoon

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Gas Project Non Divergent?

I will investigate more

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Hi, probably building simple solver could help you. Check out those tutorials, they explain how to build simple and fast fluid solver.

If I understood correctly, you need to initialize velocity volume (sampled on faces), then for each simulation step: inject into it velocities from animated geometry, do divergence-free projection, advect velocity by itself and repeat... Probably you might need to enforce boundaries to zero out velocity within geometry.

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maybe this way

prev_pyro.hipnc

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Posted (edited)

Thank you very much again! Unfortunately I had not time to implement those features into my setup. But I am studying and connecting all Houdini pieces slowly. I have attached my current setup, if anybody else is also interested. Actually, I have a static mesh, I "dent" it with VDB smooth (masked) ... then I compare smoothed/nonsmoothed, which gives me the "originally" sharp areas. I use @petz 's wrangle to calculate min curvatures then. I unify the directions of min_curv_vec regarding to an arbitrary vector (which is not ideal, but I am not good in Python to make the unification recursive).

With the " Gas Project Non Divergent " I wanted those "curvatures" to respect moving of objects. For example ... closing fingers into a fist will bias those curvatures "outside of the fist" between fingers.

This is just my personal project, the task assignment is not fixed, comments and suggestions are highly welcome.

Edited by ikoon

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