smoke being vacuumed up

#1

I have an animation where some smoke is emitted and is than vacuumed into a tube. I’ve set up a fluid and tried to use a volumecurve field as well as a Newton field to create the sucking effect but it won’t obey. Trap inside just doesn’t work on the volumecurve even with forward advection damp and a low quality on the fluid. I either doesn’t follow properly or the fluid blows appart. I can get the fluid to move in the right direction but not be sucked down to a specific point like it would with a vacuum tube.

I’m wonding if emitting from nParticles might not be the way to go with the filed effecting the nParticles since they seem be more responsive to the volumecurve…thoughts?

#2

Maybe you can use nParticles and add in goals? I’m thinking make a small cylinder inside your little “needle” (I guess that’s what it looks like?) there and have it as a goal for the nParticles. You maybe need to use GoalUPP and GoalVPP so you can change the goal to move up the cylinder. That would create the effect as if the particles were coming into the opening of the tube and then moving upwards along it.

-Hunter

#3

Indeed. That’s what I’ll try. I was thinking their must be a way with straight fluids but I’ll be darned if I can get them to behave.

#4

If it doesn’t have to look perfectly realistic, also consider a simple emitting animation played backwards
-odd

#5

I got it to work. Instead of using particles I stuck with straight fluids. I have two Newton fields. one gently pull the fluid and the other ratches up the strength as it gets closer to the “vacuum tube”. As the fluid gets closer it feeds into a volume axis which vents the density out of the fluid. I also dropped in an emitter with negative density emission just to help it all along. File attached for future reference.

Thanks for the help.

#6

Also check out this thread…
http://forums.cgsociety.org/showthread.php?f=86&t=967385&highlight=vacuum

I have a fluid vacuum scene uploaded there.

#7

Hey Duncan!

Was thinking after re reading the vacuum thread… would it be possible to add some other Attributes besides Density, Temp, etc to the Fluid Emitter… … something like Pressure or Buoyancy?

Would that even work? Emitting Pressure from an emitter into the fluids density?

Could maybe open up new ways to achieved some cool effects.

#8

Emitting pressure could be useful, but the equivalent of emitting buoyancy would be emitting an upward velocity which one can already do.
However one can get much the effect of emitting pressure by using things like temperature pressure and emitting heat. (using negative temperature pressure is useful for creating suction, though one needs to use forward advection if one also wants density to concentrate over time )

#9

Yes but temp and heat only push upwards, right?

Pressure would allow pushing in all directions… could be useful. :wink:

#10

The temperature will also push down if buoyancy is negative. If you make temperature buoyancy zero then it will not push up or down. With temperature pressure then set to a positive value it will then push outward wherever it is hot. If you emit heat it will then push outward wherever you emit. If the temperature pressure is negative it will instead suck. You may wish to have the temperature dissipation high so this effect is only near the emitter.

One can also do things like a rapidly expanding explosion using temperature pressure combined with forward advection and high substeps.

I’ve attached a simple scene that sucks fluid into a box using negative temperature pressure and a heat emitter inside the box( which collides with the fluid and has an opening).

#11

Cheers,

But lets say you want to go from one state to the next, without keying the temperature in the Fluid Node which would make the whole domain change. Like take your scene, but a few seconds in start spitting the smoke back out. How?

It would be nice if somehow you could use the Emitter to change how the temp affects velocity to go from sucking in to blowing out.

I suppose you could actually build a little fan system and just use velocity from a spinning fan model.