Study of Multimode Characteristics Model on Open-Channel Junction and Division Flows

• Main Authors: Shr-Wei Liau, 廖士偉
• Other Authors: Keh-Chia Yeh
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/9pz335

碩士 === 國立交通大學 === 土木工程系所 === 92 === This study applies fixed-bed method of characteristics. The continuity and momentum equations of the flow are transformed into characteristic equations with the ordinary differential forms, and flow depth and velocity are solved simultaneously. The numerical model is extended to the simulations of open-channel junction and division flows. At the upstream and downstream boundaries, discharge and flow depth are specified respectively according to flow regime. Equal stage serves as the internal boundary condition for junction or division flow simulation. To verity the applicability and accuracy of the proposed model, Tamkang University’s experimental data for different junction or division angles, channel width ratios, and discharge ratios are adopted. Better simulated results can be obtained under the cases of small junction or division angles, large discharge ratios, and small channel width ratios. For the cases of steady junction and division flows, the simulated results of the former case are compared with those obtained from the CCHE2D model, and the simulated results of the latter case are compared with those obtained by the finite analytic model. Both cases show satisfactory results. This study also considers unsteady flows passing junction or division channels with rectangular and non-rectangular cross-section. The interaction and propagation processes of the flood wave in the main channel and the tributary channel are investigated. The results can provide some information for extending the model to the simulations of natural river flows in future.