"Caching" means that RealFlow | Cinema 4D writes the simulation data to disk (one file per fluid/mesh node and frame) and saves them for later use, e.g. for replaying the simulation or exchange with other programs. You can find more information about this topic under → "Caching".
Cache Folder (Mac OS X)
This is the OS X path to the folder where the simulation files will be stored.
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When you click on this button RealFlow | Cinema 4D will simulate the adjusted frame range. During this process, particles are not visible, but a progress bar informs you about the simulation's state and with “Cancel” the process is interrupted.
Remove Cache
Be careful with this button, because a click on it will remove A click on this button removes all simulation files and empties the cache folder . This (this action cannot be undone!). A new windows asks for confirmation.