Fluids Compressibility

I do not realy understand this Button (Fluids - Domain - advanced). One can compress gas, but not liquids. Or in this case it is more in the meaning of adhesion and affects the viscosity of the fluid?

Thanks for answering.

Toni Grappa

supposedly it affects how much fluid compresses under gravity, but i had never really seen any difference, plus, sometimes an extreme value can cause the simulation to become unstable. So I would just leave it alone. Lol sorry if the reply doesn’t answer your question.

Hi mpan3,
The Wiki Manual not realy gives a concrete answer, same thing with release notes. Im trying to write an article concerning the fluid System for the german BlenderWiki and the most experienced user of fluids in this forum (I might be wrong and I dont want to hurt anybody) also don`t know. Belive me, writing dokumentation sometimes can be realy frustrating :slight_smile:

Toni Grappa

I dare to say I am sufficiently knowledgable with the current fluid system, but compressibility is one of those things that I just never figured out.

You can talk to n_t about it, he is the creator of the fluid engine.

Have a look at the “Water’s Compressibility” section at:

You can find a more technical description by n_t at (Page 5):

I didn`t know that water is compressible. Gas - of cource, but water… Thank you very much for this background information.
Water at temperatures common in nature has a compressibility factor of around 0.0000034, meaning that a hydrostatic pressure of 6.89 kilopascals (1lb/ sq. in) would reduce unit volume by about 0.0000034 of the original volume.

Glad to see, that one can handle this with Blender :smiley: