found: Work cat: Chaudhry, M.H. Open-channel flow, 1993:p. 2 (The flow in an open channel or in a closed conduit having a free surface is referred to as free-surface flow or open-channel flow)
found: Munson, B.R. Fundamentals of fluid mechanics, 2002:p. 621 (Open-channel flow involves the flow of a liquid in a channel or conduit that is not completely filled. There exists a free surface between the flowing fluid (usually water) and fluid above it (usually the atmosphere). The main driving force for such flows is the fluid weight---gravity forces the fluid to flow downhill)
found: Fox, R.E. Introduction to fluid mechanics, 2004:p. 41 (The internal flow of liquids in which the duct does not flow full---where there is a free surface subject to a constant pressure---is termed open-channel flow. Common examples of open-channel flow include flow in rivers, irrigations ditches, and aqueducts)
found: Benedict, R.P. Fundamentals of temperature, pressure, and flow measurements, 1984:p. 401 (The flow in rivers, canals, and pipes that are not flowing full, that is, where one surface of the liquid is free of solid boundaries, is called open-channel flow)