Erosion-corrosion is most severe in the vicinity of flow disturbances. In the past, erosion-corrosion under disturbed flow conditions has been studied experimentally in flow loops and numerically by performing flow simulations. In this study a new, compact experimental setup was tested, intended for study of erosion-corrosion under disturbed flow conditions, involving a rotating cylinder geometry with a sudden step. A thorough characterization of this new setup was initiated, involving wall mass transfer measurements complemented with Direct Numerical Simulation of the turbulent flow around it. A large variation of the wall mass transfer rates behind the step was measured similar in character to the one obtained in flow through a sudden pipe expansion. Flow simulations have confirmed that this flow geometry will create a qualitatively similar mean flow pattern as observed in a sudden pipe expansion flow involving flow separation and reattachment. The simulations have also shown that there is a largescale unsteadiness in the turbulent flow structure downstream the step, a fact that might have a significant impact on erosion-corrosion.