D. Berzi - Politecnico di Milano, Dept. I.I.A.R., Milan, Italy
E. Larcan, - Politecnico di Milano, Dept. I.I.A.R., Milan, Italy
S. Mambretti - Politecnico di Milano, Dept. I.I.A.R., Milan, Italy
E. Orsi - Politecnico di Milano, Dept. I.I.A.R., Milan, Italy

This paper concerns the analysis of some aspects of the pressure fluctuations over the upstream face of a sill in a stilling basin. The hydrodynamic forces acting on the sill have to be known, in order to properly design such a structure; so not only the value of the average pressures, but also a quantitative characterization of the distribution of the pressure fluctuations, due to the intense turbulence of the flow, seems very important. Moreover an investigation on the non-dimensional numbers that rule the phenomenon of pressure fluctuations is necessary for a correct modeling of this type of fluid-structure interactions.