When used to measure open channel flows, packaged metering manholes most commonly integrate a flume or weir ( flumes being most common due to their ability to pass solids, low head loss, and wide operating ranges ).
22.
The energy equation used for open channel flow computations is a simplification of the Bernoulli Equation ( See Bernoulli Principle ), which takes into account pressure head, elevation head, and velocity head . ( Note, energy and head are synonymous in Fluid Dynamics.
23.
The principle of conservation of momentum in open channel flow is applied in terms of specific force, or the momentum function; which has units of length cubed for any cross sectional shape, or can be treated as length squared in the case of rectangular channels.
24.
Depths greater than critical depth are considered subcritical and have a Froude Number less than 1, while depths less than critical depth are considered supercritical and have Froude Numbers greater than 1 . ( For more information, see Dimensionless Specific Energy Diagrams for Open Channel Flow .)
25.
To the best of the author s knowledge, this final result for the alternate depth relationship appears in no textbook and is an original contribution by Dr . Glenn E . Moglen of Virginia Tech and appears on this website through the assistance of Paul Le Bel and the CEE 5984 Open Channel Flow course at Virginia Tech.
26.
In fluid mechanics, flows in closed conduits are usually encountered in places such as drains and sewers where the liquid flows continuously in the closed channel and the channel is filled only upto a certain depth . Typical examples of such flows are flow in circular and ? shaped channels . Closed conduits flow differ from open channel flow only in the fact that in closed channel flow there is a closing top width while open channels have one side exposed to its immediate surroundings . Closed channel flows are generally governed by the principles of channel flow as the liquid flowing possesses Manning's Equation, Continuity Equation ( Q = AV ) and channel's cross-section geometrical relations are used for the mathematical calculation of such closed channel flows.
