A centrifuge for selectively concentrating and collecting constituents of a biologic liquid mixture, comprising a chamber arranged to contain a liquid mixture and having a central longitudinal axis, said chamber comprising an assembly comprising a tubular barrel and an end wall, each comprising a common central longitudinal axis, said tubular barrel comprising a side wall tapering radially inward toward said central longitudinal axis from said end wall； an inlet for adding the liquid mixture to said chamber； a first port in fluid communication with said chamber and located in said assembly at a first radial distance from said central longitudinal axis； and a circumferential channel (640) extending from the interior of said barrel to said first port, said circumferential channel comprises a restricted portion and a non-restricted portion, said restricted portion comprising a restriction (800) in a least a portion of said circumferential channel (640)； and a motor to rotate said chamber about said central longitudinal axis.
