Numerical and experimental investigation of local scour downstream of a sill

This paper presents the results of a laboratory and a numerical study investigating the local scour downstream of a sill followed by a rigid apron. Nine experiments were run in clear water scour conditions, as varying the discharge. A mathematical model simulating the local scour downstream of the sill and using both the experimental velocity fields and the physical and mechanical properties of the sand was developed. The mathematical structure of the model consisted of a second order partial differential parabolic equation whose unknown is the shape of the mobile bed. The numerical integration of this nonlinear equation, with suitable boundary conditions, indicated agreement with the measured scour profiles at the equilibrium condition. Upon comparing the experimental and the numerical data, a similar temporal evolution of the maximum scour depth was observed