Experimental and Numerical Study of Turbulent Flow in Open Channels with Impermeable and Porous Bed

In order to experimentally and numerically investigate turbulent flow in an open channel with porous (vegetated) and impermeable bed 2D Particle Image Velocimetry (PIV) and a Computational Fluid Dynamical (CFD) model were used. PIV is an optical method of flow visualisation that is used to obtain instantaneous velocity measurements on a plane of a flow field. The CFD model is based on the CFX computer package, a high-performance general purpose fluid dynamics program that has been applied to solve wide-ranging fluid flow problems.In order to validate the results of the numerical model, the CFX based results were compared with experimental data from PIV measurements. The comparison is carried out for two cases: a) impermeable bed and b) porous bed. For the simulation of the porous bed a grass-like of flexible vegetation of 2 cm thickness was used. Vertical distributions of velocities above the impermeable bed and above the vegetation for the porous bed for the same different total depths were evaluated.