An Integrated Numerical Model for Unsteady Flows in Pressurized and Open-Channel Circular Pipes
Date Issued
2010
Date
2010
Author(s)
Lin, Cheng-Wei
Abstract
Analysis of flows in drainage or sewer system with circular pipes is complicated, due to open channel and pressurized flows often occur alternatively or exist simultaneously.
The difference between these two flow conditions is that open channel flow is drived by gravity force and pressurized flow is induced by pressure differences. It is impossible to analyse pipe system based on only one individual flow condition. An integrated numerical model for simultaneous pressurized and open-channel flows is needed.
The objective of this thesis is to develop an integrated model to simultaneously deal with open-channel and pressurized flows. One dimensional unsteady flow equations and multimode method of characteristics of the second kind are employed. To overcome the difficulty of the zero width at the top of circular pipes, a novel approach based on material elastic area deformation under pressures is used to replace previously popular Preissmann slot. Assuming that pressure velocity in pressurized flows is equal to sound velocity in normal temperature in order to simulate all possible conditions in sewer system. An example of open-channel flow converts to fully or partial pressurized flows is given. For a pipe network system , validity of present model is assured by checking with conservation and energy conservation in junction problem. It is shown that present model can efficiently deal with integrated flow problems in network system with reversed pipe slopes.
Subjects
unsteady flow
open-channel flow
pressurized pipe flow
celerity of pressure wave
de Saint Venant. equation
network flow
reversed pipe slope
SDGs
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