I can give ya a bad exemple, if ya randomly put in all kinds of c4d renders all going through each other one to the left other to the right etc .. That's what I would call bad flow ^^
Best description I've ever found: "A principle of visual movement in artworks, which can be carried by line, dots, marks, shapes, patterns, color and other compositional elements.Directional movement in paintings or sculptures directs the viewer's eye around or through the artwork, in a way which the artist consciously or unconsciously(subconsciously- Ambiguity) determines. One important function is to keep the viewer's eye from "leaving" the work, and instead cause the the viewer to follow an inventive(interesting) path within the work, or exit in one area, only to be brought back in another area"