flowing liquid inside a pipe

[Steve Roberts]

If it doesn’t have to be realistic, how about drawing a line (open mask on a solid) then applying the Stroke effect to that solid, animating the end point to make the line grow?

[Aqeel Sami]

if it is somehow realistic it would be better and thank you in advance.

[Tristan Nieto]

Try this:

Make a new solid, trace the layout of your pipes as a mask onto the new solid. Apply particle playground and then in the wall property, set the boundary to the mask you’ve created. Pick a point where you want the fluid to start and make sure the barrel radius is within the mask, otherwise particles will bounce out.

Once you’ve got that, play around with the physics of the particle generator to get it moving more like a fluid. I recommend adding lots of particles (around 200 per second) and make them largish, at least 5 px. Then precomp it or use an adjustment layer to add the Roughen Edges Effect. This will allow you to get rid of all the square corners and make it look like a single, fluidic blob. Things like CC Glass are also good if you want to give it more of a shape.

However, you can’t really do much with the particles once they’re generated. So don’t ask too much of them. They wont do things like make waves, create pressure or follow paths, but if all you’re doing is filling a space with particles it should work for you.

Good Luck.

Tristan Nieto
Visual Effects & Motion Graphics
tristannieto.blogspot.com

[Will Cavanagh]

If you need it to be very realistic and are willing to use more expensive/complicated software, you should check out NextLimit’s Real Flow.

getnmd.com
nationalboston.com

[Tristan Nieto]

I second that. If you’re ever going to be doing more than one fluid animation then Real Flow is invaluable.

That being said, I’ve actually been able to get some really good fluid simulations out of Blender, which is free, but it’s not that user friendly for those unfamiliar with 3D.

Tristan Nieto
Visual Effects & Motion Graphics
tristannieto.blogspot.com