# How can I make drops of fluid hang from a surface?

The images below display the kind of effect that I'm looking for. A combination of surface tension and intermolecular forces make drops of water hang on things (though they may occasionally fall off depending on the amount of fluid in the drop). I can't seem to figure out how to do this with the fluid simulator though--every time I try, the fluid just beads off like the object is made of a hydrophobic material; as soon as it reaches the side of the obstacle, it falls, rather than curving to the surface like my diagram.

I've already tried using various combinations of No Slip, Partial Slip, and Free Slip on both the obstacle and the domain but I can't find the right combination.

• I think it is worth mentioning that if you want to do this for a still, it is almost certainly going to be better to fake it. – VRM Apr 23 '19 at 18:49
• @VRM That's disappointing; I was hoping for a decent generalized solution. If one can't be given, ideally, I would like to see answers for both animated and static blends. Could you elaborate on how you would go about in creating an accurate fake? – thepufferfish Apr 24 '19 at 16:27
• There is no quick way to do this in animation. For a still, the particle system and some hand modelled droplets would do. For an animation; if the fluid system doesn't work out for you, maybe try with a particle system with metaballs and dynamic paint like in this link: blenderartists.org/t/looking-for-recommendations-rain-on-glass/… – Abel Apr 24 '19 at 22:14

Apply a strength 5 force field to both the fluid and obstacle. The fluid should probably have a low partial slip, and free flip on the object. I would be more precise if I had more time, but here's my result (see below pic). You can see particles starting to stick, then fall off near the very bottom.

How it works: Water molecules have a charge of attraction to each other (and solid objects) causing surface tension, which holds a drop together. applying the force field tries to imitate that effect.

If you want to use fluid sim you can also keyframe the speed value, changing from 1 to 0 (no motion), in the fluid sim panel as it's shown below.

Anoter way is to model a drop, halve it and use as hair particles with vertex groups.

The best way that I know of to do this, assuming you just want a still, is to do it through metaballs. Set up the object with the metaballs so that they diffuse onto the glass, but remain off from it enough to look like a droplet. If you do multiple of them, you can animate them, although it will not look the most realistic. Alternatively, use this tutorial https://www.youtube.com/watch?v=sO8kw0a2ZeI on how to make a rainy window, and apply it to the effect that you want.

Basically you need to create a Fluid Simulation and grab the Key Frame from it. There is an Add-On called FLIPFluids but it is \$76 https://www.blendermarket.com/products/flipfluids.