RealFlow Official Forum

Why are "liquids" in RF able to be compressed? Is it not so in nature that fluids are non-compressible? When trying to settle particles in a container, the springiness of the particles can be quite bothersome and time consuming. I can understand making gases and dumb particles compressible, but the expanding and contracting of RF's liquid particles confuse me. Based on resolution, shouldn't there be a set distance between particles that is unchangeable unless pulled apart or joined by external forces? Can you comment on this?

You are right, real life liquids are almost non-compressible but our particle fluid solver approach just try to approximate that non-compressibility condition using some specific method that doesn't guarantee it. There are other methods that can achieve that condition but they have their own problems. Remember that our grid fluid solver can achieve non-compressibility very well (you have the compressibility parameter to control this).

I hope this helps.

atena wrote:There are other methods that can achieve that condition but they have their own problems.

Thanks for the answer. Can you elaborate on this part? What are the inputs that allow control of compressibility?

Hi Brian,

if you are interested in those matters, here's a book that sums up CFD for graphics very good:

http://www.amazon.de/Simulation-Compute ... 294&sr=8-1

It is a lot of science in it but the author tries to present that in a very interesting way.