A planar plunging jel can drive penetrating, attached, wavy or tranquil flows depending on its plunge angle and the geometry of the receiving chamber. Geometries considered here include supported and free-fall weir flows into a rectangular receiving chamber, and idealised siphon-priming model configurations. The very different air entrainment, detrainment and net transport characteristics of these patterns have practical importance for the design of aeration and downshaft hydraulic equipment as well as the priming of large siphon units. Two main studies are reported here, the first concerned with classification and characterisation of some main features of the flow patterns, the second with predictive calculations of bubble transport and detrainment in penetrating flows - the pattern of most practical concern for many applications.