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Collision relationships in FLIP

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Have some various questions on how to setup collision relationships with the FLIP solver, and maybe my approach to this is wrong (I'm coming at this with a Realflow mindset for fluids). Not so much trying to achieve a specific effect as I am understand how to wire everything into FLIP.

These are somewhat basic questions (I think), but I've yet to get them working. In this example I've got an initial fluid, and would like the continuous source not to be affected by anything other than gravity. Basically it would push around the initial state fluid, but not have the adverse effect.

If there are 2 sources, how can one source be pushed by the other but not the other way around? As to setup exclusive linking of sorts.

With the 2 sources, can one source collide with a specific RBD and not the other? Essentially having the continuous emitting fluid not collide with the RBD and just be killed by the sink box as it travels through.

Now that FLIP is getting more widely used its time to figure it out. Any help or pointers would be greatly appreciated. Cheers!

Anthony

fluidBubble.hip

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Have you tried separating the sources into separate flipobjects and merging them with a non-mutual relationship? Maybe turn Feedback Scale on the solver up to 1 for good measure

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If there are 2 sources, how can one source be pushed by the other but not the other way around? As to setup exclusive linking of sorts.

With the 2 sources, can one source collide with a specific RBD and not the other? Essentially having the continuous emitting fluid not collide with the RBD and just be killed by the sink box as it travels through.

There's not an easy way to do this within one simulation, as currently all collisions and inter-fluid pressure forces are global to a particular flipfluid object. Your best bet is probably to do it as two simulations: the first one containing the fluid that should push the other fluid around and ignoring collisions; the second then takes the velocities from the first simulation as an input.

I set up an example with the following steps:

- disable the second source and the RBD collisions in the first simulation

- copy the DOPnet to a new one

- turn off the first source and re-enable the second source and collisions in the copied DOPnet

- set the copy to be the "Current Simulation"

- run the "Pump from Objects" shelf tool to import the first simulation's velocities into the second simulation.

You could do this within one simulation if you wanted to get really tricky, using two flipobjects and copying velocity fields from one to the other, but I think I'd do it as two sims for flexibility.

fluidBubble_pump.hip

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Ah, thanks man. Had a feeling trying to do all this in one dopnet would get convoluted very quickly. This does what I was after....probably didn't post the best example file, but was really just curious what others would do for something like that.

I had tried the two flip objects and got some sort of reaction with them together, but the result was weird and didn't seem like the best solution. Thanks for the the new file!

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