Cavitation is a destructive phenomenon in flows with high velocity, and becomes more critical in curvatures. Therefore, adequate consideration in design of curvatures is a necessity. Furthermore, it has been suggested that aerators should not be used in the design of curvatures. Consequently suitable design of curvature without cavitation is very important. In this paper, various curvature profiles have been defined and compared with each other and the optimal profile has been selected. For this purpose, curvature profiles have been determined using different methods such as: "constant cavitation number profile", "controlled pressure profile", etc. In the design of flip bucket curvature, cavitction index in the upstream end of curvature is very important, which must be more than its critical value at the upstream end and along the curvature. Different curvature profiles have been evaluated for the flip bucket of Silve dam spillway. The best curvature profile considering economic and hydraulic parameters has been resulted from the controlled pressure profile method using cosine pressure distribution function. In this profile, the upstream end of profile is similar to the rotational assumption profile of constant cavitation number. In this case study, the length of curvature is 45.24 meters and maximum value of the cavitation index is 0.2648. Cavitation index values in the upstream and downstream end of curvature are equal to 0.2139 and 0.2248, respectively.