Author(s): Tapas Kumar Pradhan; Venu Chandra

Linked Author(s):

Keywords: Spur dike; Anisotropy invariant map (AIM); Invariant function (I.F); Kolmogorov length scale (η)

Abstract: Local scour near the spur dikes is hazardous to its stability. Obstruction provided by spur dike to the main flow leads to a three-dimensional vortical flow field around it. The interaction of complex vortical flow field with sediment causes scouring near spur dikes. Past research gives strong evidence regarding role of the vortex system (horseshoe and wake vortices) in sediment lifting and transporting around spur dikes. The present study uses turbulence anisotropy and length scales to characterize the vortices at different zones the thalweg, recirculation, horseshoe, deposition, and wake regions. Experiments were conducted with a straight spur dike under clear-water conditions. Turbulence anisotropy is discussed using the anisotropy invariant map (AIM) and invariant function (I.F). Data plots in AIM show that the anisotropy rises as we get closer to the bed, suggesting the creation of turbulent kinetic energy near the bed. In the thalweg region, shape of the eddies remains the same throughout the depth. The turbulent length scale (Kolmogorov length scale (η)) is calculated at different zones. Kolmogorov length scales increase with water depth, indicating that the turbulent kinetic energy (TKE) dissipation rate is lower at the water surface.

DOI: https://doi.org/10.1007/978-981-97-6009-1_20

Year: 2022