Numerical Simulation and Experimental Investigation of Flow Over a Cylindrical Weir Considering the Influence of Roughness Using the Standard k-ε Model

In terms of the nature of flow profile over weirs، cylindrical weirs are classified as short-crested weirs. Advantages of the cylindrical weir shape include the stable overflow pattern، the ease to pass floating debris، the simplicity of design compared to the ogee crest design. In the present study، numerical simulations of overflow cylindrical weir with smooth and rough surfaces were done employing two sizes using the standard k-ε turbulence model. The free surface was determined using the VOF method. Results showed that the k-ε turbulence model and the VOF method for predicting of the water surface and flow discharge were suitable، and the relative error of the predicted water head and measured value were within 1-4 %. The effect of roughness in a cylindrical weir on the characteristics of flow، such as discharge coefficient، were studied and compared with the results of previous studies. Predictions according to the Dressler’s theory and the horizontal velocity distribution obtained from the flow function over a curved bed are also presented for comparison.