Abstact The main objective of this study is to improve our knowledge about the velocity profile and turbulence within and over a permeable bed. The study was using computation fluid dynamics (CFD) methodology to simulate the studied cases. It includes a detail analysis for two-dimensional fully developed turbulent flow over and through a permeable bed. Five different cases were simulated numerically. The analysis is set for the three flow zones (free stream, porous, and interface). The detailed two dimensional flow simulations were subsequently validated using previously published results, then it was specially averaged to overcome the heterogeneity of flow. The focus in this study is on the effect of porosity and free stream thickness on longitudinal and vertical velocities in different flow zones. On the basis of this study results, it is shown that the flow velocity within the porous zone increases with bed porosity, and decreases with increasing the water depth. It is also confirmed that the turbulence parameters (turbulent kinetic energy, turbulent dissipation rate, and turbulent kinetic energy production) penetrate practically throughout the whole porous layer to reach maximum values at the interface then decreases smoothly to minimum at the water surface.
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