Effects of asymmetric undulations of a flexible foil on a flow over a square cylinder have been evaluated using two-component particle image velocimetry (2C-PIV) and hotwire anemometry (CTA). An intermediate flow regime is chosen for the study. A comparison between the symmetric and asymmetric undulating foil have also been drawn. The long foil is chosen for the study. The results reveal that both the symmetric and asymmetric undulation foil suppress the vortex shedding phenomenon of the bluff body. The asymmetric undulation of the foil deflects the wake thus breaks the symmetry of near wake, which infers to the positive lift generation. The undulation foil also modulates the mean drag of the bluff body. The asymmetric undulation of the foil proves to be better wake manipulator than symmetric undulation.