Numerical Modeling of Unsteady Flow in an Open Channel with Non-constant Bottom-slope
Date Issued
2005
Date
2005
Author(s)
Lin, Mong-Ie
DOI
zh-TW
Abstract
The study of open channel flow with changes in the bottom-slope has been a focal point of some river-mechanics engineers. When encountered with such bottom-slope changes, the engineers may witness the flow varying between subcritical and supercritical states, which is commonly known as the transcritical flow. The analysis of flow variation due to the bottom-slope change, with the transcritical flow in particular, poses a highly difficult and challenging problem. In the past, it permitted solutions only under relatively simple channel configurations and under the steady flow state. The analysis of unsteady flow, which is a very complex phenomenon normally described by nonlinear partial differential equations, has become numerically attainable only after the computer coming into existence. The purpose of this thesis is to prepare a numerical model which can compute unsteady flows in a channel with changes in the bottom slope, and subsequently to put the model to a series of flow tests under four basic forms of bottom-slope transition. Before this, the results from a set of steady flow cases using the present modeling method have been compared carefully with those by the traditional method in order to ascertain the model reliability. It is believed that the modeling study made in this thesis can afford useful guidelines for the flood wave moving down river channels having various bottom-slope changes.
Subjects
不恆定流
多方式特徵線法
unsteady flow
mmoc
Type
thesis