View Full Version : Fluid...help

04-13-2006, 04:54 AM

I was wondering if anyone has any proven methods of creating a realistic fluid motion. Basically I want to make a 'juice' effect that pours from a can and lands in my mouth(I'll do the editing in After Effects).

I've just been having some problems.

Using Lightwave 7.5, I made an HV Emitter and addded HyperVoxels 3.0 Volumentrics with a Stretch Amount of 600% and Particle Size of 240mm.
However, it just looks like blobs than one fluid motion.

Anyone care to help out ?

Many thanks,


04-13-2006, 06:22 AM
First the emitter:
Start with a proper emitter size. 1x1x1m is a realy big can. If the outlet is unproportional all the other effect's like gravity or speed are hard to tweak.
To make the particle falling use only the Y Gravity. For a starting speed rotate the emitter so the particles flow to say X and set a velocity in the X direction (tweaking tweaking).Increase the particle Birthrate. Maybe 2000 for the beginning. The more particle, the better the effect.
Don't start with HV as long you are not at least a little happy with the flow.

The particle should fit the can size. For a can with a 10cm x 10cm outlet you can try say 5mm. After the particle merge a little better you can set the Stretchamount and Sizevariation (maybe values about 20%). When a fluid is falling it doesn't stretch this much.
Effect's like transparency and Reflection should be set at last - they take long to render.

Happy tweaking.

04-20-2006, 08:14 AM
I've attempted the fluid idea, but I don't think I've quite pulled it off.

Any suggestions or helpers would be greatly appreciated.

04-20-2006, 09:26 AM
This may be a start for a liquid:

04-20-2006, 03:02 PM
You might be able to do it in blender and import it into lw as an object sequence. A lot of pain but it migh be worth the effort.
Also I remember seeing a tutorial about something similar. The idea was to use morphs(you can probably use bones with that too) to make the liquid object bend and go in the direction you want. A displacement and/or a bump map can be used to give the effect of flowing liquid I guess. This is not going to be super realistic though.

I was never able to do any decent liquid with hypervoxels. I suck :D

04-20-2006, 11:20 PM
it is VERY difficult to create any type of laminar flow with HVs; by their very nature they are not inclined to do this. This is because it uses a purely eularian approach--particles.

I would reccomend blender. It's free, physics based, and not too bad. Because (iirc) Blender's fluid dynamics system is at least sem-lagrangian, its not really like mixing a bunch of metaballs, and getting a smooth laminar flow is much easier. There are, however, some limitations--

first off, im pretty sure the object sequence doesnt work with motion blur... well at least i remember reading something about that.

secondly, Blender uses the Lattice Boltzmann Method, which is one of the physics-based fluid dynamics solving methods. IIRC, the LBM slows down as viscosity decreases. As such, Blender is ideal for thick, gooey flows, but will take you longer to calculate thin, watery stuff... of course i could be wrong on all of this... but whatever.

04-21-2006, 02:50 AM
Thankyou very much indeed for your help, especially the example files, they look fantastic. I shall play around with that I think :thumbsup:

You're right, its difficult with HV to get it just right, still a really impressive plug-in nonetheless.

Thanks again!

04-21-2006, 02:59 AM
I see that a free flow noise shader has just been releassed, see www.flay.com as usual.

Could be very handy!