If someone can take a look at my blend file and tell me what I did wrong. I'm trying to follow some YouTube videos, but I'm not sure how to get the water to work. I managed to get some water to work, but it flowed out of the bulb like it wasn't even there, and then there was a hidden rectangle around it that kept the water within that I never put there. And all of a sudden, the whole bulb itself turned solid black. I had to revert to a previous save because I have no idea what I had done. I'm just trying to make the water stay inside the bulb, so I can animate the cube drop in the water, then animate it floating in it.

I was able to get the water to come back, and this time I took a picture of how it reacted.

enter image description here


The “cube [you] never put there” is the fluid domain: the little world that the fluid operates in. Fluid can be allowed to leave this domain by changing some settings, but it will never return.

Did you set the bulb as a fluid effector + collision object? Did you set its influence to mesh? Did you make sure that the normals were pointed inward so that the liquid would stay inside and not stay outside? Any of these not being the case will cause the fluid to ignore the bulb or misbehave.

The cube will not be able to “physically” float in the water, but you can animate it manually, and you can even set it as a collision object so the fluid reacts to it; just not the other way around. I recommend using some elastic interpolation for bobbing, and maybe noise curve modifiers in the graph editor for slight sideways motion.

IDK why your bulb went black. That doesn’t sound related to the physics, but the tender engine. Maybe the fluid physics caused bad data to get sent to the engine, though.

For more information, see the Blender manual on fluids.

Hope that this helps.

  • $\begingroup$ Is the normal pointed inwards the red and blue faces? Someone on here showed me that yesterday. Can i set the bulb shape as a domain so the water stays inside it instead of the box it created. I'll look into that animation tips you mentioned for the cube. I've tried to view the graph editor but it looks confusing. Thank you for the help. I did end up getting flexfluid but i can't get the water materials to show up so im just having complete trouble with water regardless what i use. $\endgroup$ Jul 2 '21 at 6:49
  • $\begingroup$ @adlowe07 no, normals are not visible by default at all, only their results. No, the domain shape will always be the bounding box cuboid of whatever the original mesh was, and will erase it to replace it with the new fluid mesh. Read up on animation first: docs.blender.org/manual/en/latest/animation/keyframes/… FFR, it probably isn’t a good idea to buy a new tool because one was having trouble using the free one correctly :-( but then again maybe it has an easier interface because they worked more on it. $\endgroup$
    – TheLabCat
    Jul 2 '21 at 7:22

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