One of the most important factors in designing spillways is to consider sufficient discharge capacity.
Possible creation of negative pressure over spillway during high flood conditions can be a potential for
occurrence of cavitation damage. Flow aeration might be one of the best ways to prevent this
phenomenon. Realizing the air detrainment process along the chutes is a key problem in designing
aerators. Although experiments on hydraulic models have their own advantages, but these methods are
expensive and time consuming. In this study the CFD code FLOW-3D® has been used to determine the
spillway flow air concentration in case of aeration by means of deflectors. Comparison of obtained
results with the Kramer's experimental results shows good agreement. It has been realized that the
flow bottom air concentration downstream of deflectors reduces exponentially.