Device for the fractionation of a fluid containing particles and for the extraction of a volume of interest

A device for fractionation of a fluid containing particles, and for extraction of a particle-lean volume and of a particle-rich volume, comprising:

• a cylindrical reservoir including at a first end an inlet orifice configured to supply the reservoir with fluid in a direction of pumping from the first end toward a second end of the reservoir;
• a fractionation body, extending along a central axis of the reservoir in which it is housed, between an upstream end and a downstream end, the upstream end of the fractionation body being positioned in vertical alignment above the inlet orifice, a cross section of the fractionation body reducing at its downstream end;
• the fractionation body defining, with the reservoir, a first passage opening at the downstream end onto a zone with a geometric singularity configured to form a recirculation zone downstream of the downstream end;
• and
• extraction means, situated downstream of the fractionation body, configured to separate and extract the lean volume and the rich volume, the extraction means comprising a partition, or an annular partition, delimiting an extraction volume configured, as fluid circulates in a direction of pumping, to receive a particle-lean phase formed in the recirculation zone in the region of the partition.