The present invention relates to solid bowl screw centrifuge comprising a centrifuging chamber having a rotatable screw with a center axis and a rotatable drum surrounding the centrifuging chamber. Also included is an axially extending inflow tube for guiding material to be centrifuged into a distributor. The distributor is oriented in a substantially perpendicular manner with respect to the center axis of the screw and configured for introducing the material to be centrifuged into the centrifuging chamber. The distributor further includes at least one wall having a surface structure that includes projections configured such that a substantial portion of the material to be centrifuged flowing through the distributor must flow around at least one of the projections.