RealFlow | Cinema 4D's simulation settings are located under the "Scene" object's "Solver" tab. During your daily work you will mostly deal with "Substeps" and "Iterations":
- Substeps determine the quality of the simulation.
- More substeps mean better, more accurate results, but also longer simulation times.
- The default settings ("Auto Params") work very good in scenes without interacting objects, e.g. pure liquid or granular simulations.
- In conjunction with collision objects, the default values are normally not sufficient.
- Increase the substeps in moderate steps, e.g. by 2 or 4 until you get the desired result.
- The → "Liquid - SPH" fluid type works with rather high substeps already (Min = 1, Max = 300) and here it is normally not necessary to increase the values.
Iterations are only relevant with "Granular", "Viscous", and "Viscoelastic" fluids, as well as the "Elastic" deformer:
- More iterations add viscosity and stiffness to the materials mentioned above, so be careful with high values (approx. greater than 50 or 75).
- Iterations are applied per substep: if you increase the number of substeps you will always get more viscosity/stiffness. Decrease iterations if necessary.
A few more notes:
- "Number of Threads" specifies the number of processors/cores for the simulation. You will hardly see any boost in simulation time with more than 32 threads.
- "Use Geometry Velocity" is only relevant if your project contains animated objects.
- "Use GPU" activates the simulation via your graphic card. We recommend reading the → linked page for more information about what's important.