Numerical investigation of flow around an isolated spur dike in a curved channel

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Öğrenci: EZGİ BUDAK

Danışman: METE KÖKEN

Özet:

Secondary currents generated by meanders of the rivers cause scour along the outer bank of the rivers if the bed material is erodible. For this kind of rivers spur dikes are located along the outer reach where they regulate the flow and prevent erosion of the outer bank. In a highly curved channel several streamwise oriented vortices form within the bending section. However, presence of a spur dike causes the formation of some additional coherent structures such as horseshoe vortices and wake vortices. In fact, the interactions among these vortices and the secondary circulation results in a highly three dimensional complex flow field within the channel bend and around the spur dike. In order to be able to investigate the coherent structures and their interactions among each other eddy resolving method Detached Eddy Simulation was used in the present study. Different spur dike configurations were tested to understand the changes within the flow field and the coherent structures in a 180 degrees channel bend which has a flat bed. The results show that the presence of the spur dike decreases the pressure root-mean-square fluctuations value and the spur dike orientation which lies in the flow direction is disadvantagous as it increases the bed shear stress considerably.