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English: Diagram of an arbitrary volume partitioned into several parts, used in a proof of the Divergence theorem. It illustrates that the flux of a vector field out of the original volume is equal to the sum of the flux out of the component volumes. This is because the flux through the partitions (green surfaces) is positive for one volume but negative for the other, so it cancels out in the sum.
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Captions
Diagram of an arbitrary volume partitioned into several parts