Hydrokinetic turbines, such as Savonius turbine, are used to extract the energy from the flowing water stream, without or with very limited change in the natural path of the water flow. The performance of the Savonius turbine can be improved by geometrical modification of the vanes. In this investigation, three different semi-circular blade shapes have been selected for analysis: (i) Vane with both edges having a semi-circular edge, (ii) Vane with a sharp outer edge and semi-circular inner edge, and (iii) Vane with a sharp inner edge and semi-circular outer edge. The 2D simulations are used in the present investigations. The grid-independent study, domain optimization, and validation of the adopted methodology are carried out before investigations related to the vane shape. The obtained results are indicated as a non-dimensional parameter of the coefficient of power (Cp) and coefficient of torque (Ct). The power coefficient obtained with the optimized design is 0.24 against that of 0.08 with the conventional vane shape.