View Full Version : simulating fluid in a pipe

05-28-2003, 12:57 PM

does anyone have any ideas?
i tried using hypervoxels, but i wasen't very happy

i couldn't get them to fill the pipe and take on it's (the pipe) shape
it ended up looking like half digested food flowing down someone's small intestine!!

05-28-2003, 01:49 PM
Look on the bright side, one day someone will want to know how to make a small intestine digesting food, and we'll all tell them you are the go-to guy for that! ;)

Sorry, other than offering a little humor, I have nothing useful to say. :cool:

05-28-2003, 03:22 PM
depends on what, how and where the fluid is going......you could use HVs..or you could model the fluid...but more details are needed to help ya out...

John Fornasar
05-28-2003, 07:19 PM
like Howard said, more details would be better... realistic? technical quickie?

I do a lot of quickie "gas and steam moving through pipe and equipment setups" for training, and just need to give the illusion of movement through the systems. Here's my fast method...

I have a library of pipe types (nipples horizontal, nipples vertical, elbows, etc.)

They are created from disks and I split them in half so I can make the front half transparent at the beginning of the animation. I make the back section double sided. I use a stretched 90% tube of the rear section as my "gas" (or fluid in your case).

I put a texture on the gas surface moving (lets say in the x axis) during the animation for the horizontals, y for the verticals). Elbows I add some y movement.

Looks decent, renders fast, and the technicians watching it understand what's being taught...

Haven't bothered with realistic since LW4, but the only changes I would make would be to morph the gas surface in the elbows to get a smoother "flow".

05-28-2003, 09:19 PM
thanks for the response...

i'm very new at this stuff. what i would like to see is probably overkill for the application.

i would like to show the progression of a fluid....

what the hell.....the person that i'm working for is dabbling in virtual process control.

i'm sure that the only real benefit if for training, and for the sale of a concept.

i would be most appreciative if you could send me an example.

it has to be simple, there aren't the funds or the drive to go into depth. i could really use some help.

what about showing flow of a liquid, and the cavitation associated with the opening and closing of valves?

much thanks for any help that you can offer me.
i would really like to learn more about 3d... i'm itching for some insight. i've been no less but awed by what i've seen so far....
lightwave has been nothing less than a monumental learning curve!!

05-28-2003, 09:22 PM
ahhhh howard........what is a HV....

i'm sorry ...and i appreciate your time...but....
i must plead ignorance!

head worm
05-29-2003, 05:09 AM
I know exactly how to do this kind of stuff. Do you have a couple of days to spare?!

Water and turbulent flow is one of the most complex subjects to represent realistically both for animators and phsyicists. Albert Einstein actually tried to tackle the problem of how to predict turbulent flow and was completely beaten by the whole subject!

If I was doing this, I would use two separate elements - one to represent the liquid flowing and the other to represent the bubbles that also get created within the liquid as it sloshes around.

The liquid I would almost certainly model. This would involve creating ribbon shapes that I could make specifically fit the pipe in modeler. I'd treat each one separately as later this would mean I could randomize them nicely to make a more turbulent effect.

To get the motion through the pipe, I'd use morph maps and probably a bone chain to make them fit the pipe if it bends and twists. You basically model the liquid 'ribbons' at their fullest extent, then create a morph map and shrink them right back to almost nothing, which repesents the start of the flow motion. Using Morph Mixer in Layout, you can then expand them out over time to 'flow' down the pipe.

The technique of morphing over bones, you'll need to find another tutorial on. There is one about moving a slug over paving stones which gets this idea across. I think you can find this through Newtek's site.

to create the liquid look would require some sexy surfacing of those liquid 'ribbons'. If you animate the texture as well as the ribbons, the sense of turbulence will be further increased.

For the bubbles within the liquid. I'd use a particle emitter and move it along a path derived from the liquid model. If you keep the tip of the emitter always at the end point of the liquid, with points blown backwards into the liquid, you'll get some really nice bubble effects. You can use the pipe as a collision object to stop bubbles leaving the pipe.

My god! I've only scratched the surface. This kind of epic procedure is the mainstay of creating chaotic turbulent animation, so you have to know what you're getting into before you tell a client you'll do it for $100!!

I hope this is at least a start.

Head Word

05-29-2003, 07:20 AM
much thanks to the head worm!!

05-29-2003, 07:36 AM
much thanks to the head worm!!

05-30-2003, 03:58 PM
Still think HV would be a interesting solution.