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The original object is kept and the fragments are grouped under a → MultiBody. If you do not need them any longer the steering and the original object can be deleted.
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This option only works with a → MultiBody. When enabled RealFlow treats the MultiBody's individual objects as one object and you will see a propagating pattern.
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With this option it is possible to store the fragments of the zones with higher and lower concentration in as two individual → “MultiBody” nodes.