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A three-dimensional flow model for different cross-section high velocity channels

Home > Research > Abo A.

Director of studies: Prof. Deborah Greaves

Funded by Iraqi MOHEASR

Student: Abo A.

 Problem statement

 The development of many cities in the Kurdistan region, and the associated municipal expansion into several floodplains, has resulted in high volumes of rainfall runoff, which frequently causes significant increases in river discharge and other high velocity channels such as sewer systems. These increased discharges may lead to floods, which may cause damage to property costing millions of dollars and also loss of life (Stockstill, 1996). To overcome this problem, the design of high velocity channels that can cope with this increased demand is imperative.

The aim of this study to determine to what extent CFD theory as used in numerical research was useful in developing better designs for high velocity channels, in order to protect the municipal area against flood. To that end, this study offers a use of CFD with HPC in order to avoid the drawbacks of scale effects. Beside the prediction of the free surface flow profile, it is also necessary to find whether the channel and the bridge pier are subject to the hazards of cavitation damage or not.  It is important to check the foundation of the bridge piers against scouring as well.

Beside the design of high velocity channels featuring bridge piers this study investigated the cavitation and scouring phenomena. The CFD ANSYS-CFX-12 with HPC was used. The code is based on the finite volume method, and used volume of fluid VOF of Hirt & Nichols (1981) to predict the free surface flow profile. The study also demonstrated that for this configuration of flow environment, the hypothesis of steady state and incompressible flow  is correct, and the standard  turbulence model, which is less expensive computationally than the other Reynolds averaged Navier-Stocks equation,  RANS, can be appropriate.

This would open new issues for more design alternatives in a shorter period of time and lower cost. It is expected that CFD will be shown to be a useful tool for this application, and widely used in the future. Also, the data from this research will be used to create diagrams and may be used for design purposes.

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A bridges in Qaladze-Arbil-Iraq toppled by a flood in 2013

Typical lined open channel with single bridge pier