Abstract: In a centrifugal separator for separating mixtures into at least two fractions, especially one liquid fraction and one solid phase fraction, where there are permanently open outlets from the rotor for the fractions, there is a need for an automatic control of the flow of at least one of the fractions, especially the solid phase fraction. The invention provides in the outlet a vortex fluidic device which is of a type that does not separate the incoming mixture but which controls the flow by increasing same when the viscosity of the flow increases and vice versa. Thus, there is provided an automatic flow control; and there is a restriction of the flow without reduction of the flow area, which is important for the discharge of the solid phase fraction flow in this type of centrifugal separator.