The present invention relates to a turbulence element for use with a rotor and a rotor featuring turbulence elements. The rotor is used in a screening apparatus of the pulp and paper industry. The turbulence element has a longitudinal centerline (CL); two longitudinal edges, a leading edge and a trailing edge; two opposite ends, a first end and a second end; and two surfaces, a top surface and a bottom surface arranged between the leading edge and the trailing edge. The top surface is divided into a leading surface having its origin at the leading edge, and a trailing surface having its origin at the trailing edge. The leading edge and the leading surface are provided with undulations (U).