Session
Session 11 2022
Start Date
10-27-2022 12:00 AM
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Sarkar M., and Sarkar, S. (2022). "Laws of Turbulence and the Estimation of Turbulent Kinetic Energy Budget for Flow Through a Degraded Channel-Bed" in "9th IAHR International Symposium on Hydraulic Structures (9th ISHS)". Proceedings of the 9th IAHR International Symposium on Hydraulic Structures – 9th ISHS, 24-27 October 2022, IIT Roorkee, Roorkee, India. Palermo, Ahmad, Crookston, and Erpicum Editors. Utah State University, Logan, Utah, USA, 10 pages (DOI: 10.26077/bd87-97c0) (ISBN 978-1-958416-07-5).
Abstract
This present study focuses on the laws of turbulence and estimation of the turbulent kinetic energy (TKE) budget for flow over a bimodal degraded bed under equilibrium conditions. The analyses of turbulence were performed based on the three-dimensional velocity data captured by using a Vectrino velocimeter. The streamwise velocity and Reynolds shear stress profiles show an excellent agreement with the existing literature. In view of the advancement in the direction of bed degradation, the measured velocity data captured at different streamwise locations (before, on and after the maximum equilibrium depth of degradation) were further processed to explore the scaling laws of turbulence and TKE budget based on structure functions data. To this end, the second-, third-, and mixed third-order velocity structure functions were estimated. The structure functions data indicated the existence of inertial subrange within lower ranges of the time-lags and confirmed their agreement with the Kolmororov’s 2/3-, and 4/5-, and Monin–Yaglom’s 4/3-laws. However, the TKE dissipation rates estimated by Kolmororov’s 4/5- and Monin–Yaglom’s 4/3-laws of turbulence show significant differences in their values. The TKE budget results show that in the vicinity of the degraded bed, TKE dissipation rate is more than that of TKE production and turbulent diffusion rates. On the other hand, the pressure diffusion has larger negative values in the near-bed. However, all the turbulence parameters show no significant differences at as one moves from the initial bed-level (bed-level measured before the detachment started) to the free-surface.
Laws of Turbulence and the Estimation of Turbulent Kinetic Energy Budget for Flow Through a Degraded Channel-Bed
This present study focuses on the laws of turbulence and estimation of the turbulent kinetic energy (TKE) budget for flow over a bimodal degraded bed under equilibrium conditions. The analyses of turbulence were performed based on the three-dimensional velocity data captured by using a Vectrino velocimeter. The streamwise velocity and Reynolds shear stress profiles show an excellent agreement with the existing literature. In view of the advancement in the direction of bed degradation, the measured velocity data captured at different streamwise locations (before, on and after the maximum equilibrium depth of degradation) were further processed to explore the scaling laws of turbulence and TKE budget based on structure functions data. To this end, the second-, third-, and mixed third-order velocity structure functions were estimated. The structure functions data indicated the existence of inertial subrange within lower ranges of the time-lags and confirmed their agreement with the Kolmororov’s 2/3-, and 4/5-, and Monin–Yaglom’s 4/3-laws. However, the TKE dissipation rates estimated by Kolmororov’s 4/5- and Monin–Yaglom’s 4/3-laws of turbulence show significant differences in their values. The TKE budget results show that in the vicinity of the degraded bed, TKE dissipation rate is more than that of TKE production and turbulent diffusion rates. On the other hand, the pressure diffusion has larger negative values in the near-bed. However, all the turbulence parameters show no significant differences at as one moves from the initial bed-level (bed-level measured before the detachment started) to the free-surface.