Numerical modeling of turbulent flow interactions with vegetation in channels with fixed beds

In this work, numerical studies for turbulent flow structure, such as three-dimensional velocity, turbulent kinetic energy, turbulent intensity, eddy viscosity and turbulence eddy dissipation and secondary current in rigid emergent vegetated channel are performed using the ANSYS FLUENT software. Navier-Stokes equations and Realisable k-epsilon turbulence model are used to execute the sensitivity analyses on turbulence model and mesh resolution. The result displays that the streamwise velocity is higher in the non-vegetated region and gap region of two vegetation stem than near the vegetation area. The most negligible streamwise velocity and substantial negative transverse velocity are achieved directly behind of vegetation stem. The higher turbulent kinetic energy is observed directly behind the vegetation than the vegetation front. An increase in turbulent kinetic energy and turbulent intensity is observed as the flow moves in vegetated regions. The presence of vegetation stems along the stream significantly alters the secondary currents. The numerical model is validated and has a good agreement with experimental study. The statistical analyses such as coefficient of determination, mean absolute percentage error and Nash-Sutcliffe model efficiency coefficient also demonstrate a good fit between numerical and observed values. This work provided valuable insights into the complex interaction between turbulent flow and vegetation in river ecosystems. Understanding these dynamics is essential for effective ecosystem management and environmental conservation efforts.