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What is the minimum size requirement for a Fluid mesh object in a Fluid simulation? I've heard and read that if the mesh is too small, it may not act like fluid properly when baking. But, I don't know the exact measurements of "too small". Does anybody know?

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  • $\begingroup$ I would imagine that has to do with the limitations of floating point numbers. they are intrinsically impossible to keep 100% accurate, so if you were to make the fluid work mainly within floating point operations, minor calculations would have a tendency to be off slightly and since simulations rely on previous calculations the slight error would compound into a greater problem. im not sure if that is the case but i know that in programming of all types, double precision decimals are recommended over floating point for that very reason $\endgroup$
    – Konner Rasmussen
    Commented Mar 27, 2014 at 0:14
  • $\begingroup$ Is there a way to make my model & simulation not use floating point numbers? $\endgroup$
    – Thom Blair III
    Commented Mar 27, 2014 at 2:21
  • $\begingroup$ without a doubt... but i wouldn't know how to do such a thing myself... that would involve editing the source code, that being said, the fact is that all things in the universe are relative to their perception... so if you scaled EVERYTHING up it should reduce the effects... again, i don't know that this is the case for a fact, but it makes sense since double naturally take twice the cpu and ram to work with, the devs would opt to use single precision float. i would have added an option to change this, and their may be one, but im still relatively new to blender. maybe post in the dev forum? $\endgroup$
    – Konner Rasmussen
    Commented Mar 27, 2014 at 6:14

1 Answer 1

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This is dependent on resolution.

Imagine the domain as a grid of 3D pixels (volumetric pixels, or voxels). If your fluid object is smaller than a voxel, then it can't be represented properly (even if it's two voxels, that's still not good)

enter image description here

To fix this, you can either increase the resolution (this will increase bake time), or scale down the domain (this shouldn't increase bake time, but obviously there is less room for the fluid).

Since the resolution defines a fixed number of voxels, scaling it down will give you the same number of voxels, but they will be smaller (making the fluid object relatively larger):

enter image description here

There may be a hard limit of how small you can go eventually, but anything remotely reasonable should be fine.

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