REYNOLDS STRESS MODELLING OF OPEN CHANNEL FLOW WITH SUSPENDED VEGETATION

In this work the effect of suspended vegetation on open channel flow is studied numerically. The VARANS (Volume-Averaged-Reynolds-Averaged-Navier-Stokes) equations are solved numerically in conjunction with the Reynolds Stress Model ( RSM) of Ayotte et al. ( 1999) turbulence model modified by Souliotis and Prinos ( 2011). The effect of the vegetation density, defined by the parameter a as the frontal area per unit volume, on the mean velocities and turbulence characteristics is investigated by varying the vegetation density from 1.272 to 0.477. Also the effect of the relative gap ( height of the gap h(g) beneath the canopy over the total flow depth H) is studied with values of h(g)/H varying from 0.125 to 0.5. Numerical results are compared with experimental measurements of Plew ( 2011). Mean velocities and shear stresses are found in good agreement for all cases. Discrepancies found between numerical and experimental normal stresses are discussed.