water running down a window

[Jason Milligan]

This is the method I would probably use:

Create a comp with an animated drop gliding from top to bottom with a slight trail behind it. I would do this with various masks or shape layers.

Duplicate this comp multiple times inside a new comp, offset them physically and temporally.

I would then create a gray image with various gradients littered about to use as a displacement map on that comp. This would give variation to the movement of your drops.

[Sam Moulton]

duplicate your footage layer. Apply Mr Mercury to the top layer. Adjust to taste. Experiment with blend modes and opacity

[Jay Brown]

Hi

Tinderbox 4 plugin by foundry does rain and water droplets.

[David Bogie]

Water running down a window implies realistic interaction between the droplets. Asking how to simulate it implies you don’t need realism or you don’t know how difficult this is to do. If your need is for a stylized effect, explore all of your options in AE as described here and a search will yield tons of interesting suggestions for combining displacement maps, foam, mr mercury, rain, drizzle, and some other effects you might not think of as simulating liquids.

However, my advice is: Shoot it.

bogiesan

This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”

[Jerzy Drozda jr]

I agree with David. It’s always bast to shoot these kind of stuff, but I know it’s easy to say that when you’re not the one that has to do it, so here are some ideas.

It’s not ready-to-use recipe but it will hopefully give you and others something to think of.

Aside of the whole real-look problem (displacements, highlights, reflections and stuff) the basic problem is animating the water drops. My first try would be using some particle engine – in this case Particle Illusion instead of what you probably thought I’m going to say (Trapcode Particular). The reason I choose Particle Illusion is that it has more to do with simulations, than it has with generating cool looking particles.

I would combine Particle Illusion and Advanced Lightning to create a path that the water drops will take while pouring from the top of the window. That would hopefully create an animation of particles traveling on the lightning.

Then I’d apply some blurring filters, threshold and others to create the drop shape. Then some displacement, turbulence displacement, and finally CC Glass and Mr Mercury for final touch-ups…

I haven’t tried it, so it’s hard to say what this technique is missing, but I have a strong feeling it has something good to it and that it’s worth a try.

Good luck.
Maltaannon

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