Experimental and Numerical Study of flow patterns and turbulence intensity in lateral dead zone in a Symmetric Channel

Lateral cavities are major storage zones in riverine environments for which the mass exchanges with the main stream strongly affect the characteristics of the habitat in these dead zones. An experimental and numerical work is presented here for ten regular dead zones in a controlled symmetric open-channel. Lateral dead zones were in a different aspect ratio and water surface velocity was determined by image processing. For numerical simulation, STARCCM+ was used under LES condition. Flow pattern and turbulence intensity figures were calculated from the Image processing results and numerical data. Our results showed that the maximum intensity was obtained in boundary of main channel and dead zone, also its value increases by decreasing the aspect ratio of cavity. Maximum intensity in cavity with aspect ratio less than one, was 3 times above the cavity with aspect ratio less than one. In addition, gyres formed in regions with an aspect ratio less than one were strongly affected by the shape of the channel and no initial gyre was observed. However, in regions with aspect ratio more than one, the primary and secondary gyres were formed.