Are the boundaries between flow types on flow maps sharp or spread out?
The boundaries between flow types shown on flow type maps are actually not as sharp as a simple graphic line would indicate. This is because of two reasons: (1) for empirically based flow map correlations, there is scatter in the data used to construct the flow map; and (2) some flow transitions are gradual, e.g. for the boundary between Annular Dispersed flow and Intermittent flow, it is difficult to distinguish between highly aerated slug flow (Intermittent) and annular flow with large roll waves.
