Duct for use in a system for separating particles suspended in a fluid, and a method of designing such duct

A duct for use in a system for separating particles suspended in a fluid, the duct comprising:

• duct portions differing in shape thereof in a cross-section of the duct, each of the duct portions extending along a part of a length of the duct, the duct portions including:
• at least one basic channel portion configured to allow the fluid to flow therein along a flow direction;
• and
• at least one trapping-bay portion disposed downstream from the at least one basic channel portion, said at least one trapping-bay portion having a main channel constituting a continuation of the at least one basic channel portion and extending along a curved central line and one or more trapping bays coextensive with the main channel along the curved central line;
• wherein said at least one basic channel portion is free of trapping bays and being configured to provide a pre-determined particles distribution in the fluid flow upstream from the at least one trapping-bay portion, the at least one trapping-bay portion configured to maintain said pre-determined particles distribution while trapping at least a part of said particles in the one or more trapping bays thereof;
• wherein the main channel and at least one of the one or more trapping bays are as follows in a cross-section of the at least one trapping-bay portion taken perpendicularly to said central line:
• the main channel has a basic polygonal shape defined by at least four channel walls including an outer channel wall, an inner channel wall, an upper channel wall, and a lower channel wall;
• and
• the at least one of the one or more trapping bays protrudes from at least one of the inner and outer channel walls away from the curved central line and has bay walls generally parallel to the corresponding walls of the main channel, each of the bay walls being oriented in the same way as that of respective wall of the main channel, the area of the at least one of the one or more trapping bays being smaller than that of the main channel.