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NL Team


Author: NL Team
Publication: 20/05/2010
Category: Simulation - Type: Tutorial


“Time Step” can either be set to “Adaptive” or “Fixed”. It’s recommended to stay with “Adaptive”, but if you observe problems with interpenetration it’s also possible to simulate a scene with fixed substeps. The “Fixed” option is normally more time consuming. “Time Step” is also an option that should be defined globally under Preferences and locally for each project under “Simulation options”.

“MIN substeps” are only available with “Adaptive”. By increasing this value, the simulation becomes slower, but the level of accuracy will increase and unstable simulations might become stable. If you observe problems, it’s better to try again with moderate “MIN substeps” around 5 to 10. If the errors still persist, slightly increase this value.

“MAX substeps” are also limited to “Adaptive”. Low “MAX substeps” values accelerate RealFlow’s calculations, but at the expense of accuracy. In some cases, collision detection between particles and objects might fail due to low settings.

“FIXED substeps” becomes accessible with the “Fixed” option and subdivides a simulation into a defined number of calculation steps.

“FPS Output” normally only needs to be set once and changes should always be made under

“Simulation options” (see Related Tutorials below). The default value is 25, suitable for the PAL format.

“Threads” is adjusted automatically and normally equals the amount of detected processors or cores. Please note that RealFlow does not always use the maximum number of processors or threads, because this strongly depends on your scene. There are simulations which are better suited to multi-processor calculations, for example, projects with very large particle amounts. Other cannot completely utilize a computer’s power and therefore the processor load appears reduced. With RealFlow 5 many processes became multi-threaded, for example daemons and the new object dynamics solvers.

There’s also a single-threaded process: Python. Whenever you run a script inside RealFlow, only one CPU or core is used. That’s a principle matter of the Python programming language, not RealFlow, because Python can only support one CPU. Plug-ins, written in C++ can handle multiple processors.

“Processors” shows the number of installed processors/cores of your computer. Understandably this entry cannot be changed.

“Use max. threads” can be checked to always use the maximum number of possible threads, though it’s much better to specify this with each scene individually. Especially scenes with low particle counts can simulate faster with lower thread settings.

For the new rigid and soft body solvers there’s only one setting. Under “Quality” you can choose from three different levels: “High”, “Medium” and “Low”. Please keep in mind that this parameter can also be adjusted individually for each project under “Simulation options.” Object dynamics simulations no longer depend on “Time Steps”!.

Related Tutorials v5.x Simulation Control (beg)
Related Tutorials v4.x