Apparatus and method for directing a liquid through a porous medium

A method for directing a liquid through a porous medium, comprising:

• providing a fluidic module rotatable about a center of rotation, which comprises a fluid chamber and an inflow structure, wherein a porous medium is disposed in the fluid chamber to allow a centrifugal force-effected flow of the liquid impinging on a radially inner portion of the porous medium to a radially outer portion of the porous medium, wherein the porous medium is laterally at least partially spaced apart from chamber walls of the fluid chamber with respect to the flow, so that a fluidic connection exists between the radially inner portion of the porous medium and the radially outer portion of the porous medium outside the porous medium, which represents a bypass for a liquid flow not through the porous medium between the chamber walls and the porous medium, wherein the inflow structure is configured to limit centrifugal force-effected inflow of the liquid to the radially inner portion of the porous medium to a first flow rate, and wherein a design factor D corresponding to a ratio of the first flow rate to a maximum possible flow rate through the porous medium is not greater than two;
• introducing the liquid into the inflow structure;
• and
• rotating the fluidic module about the center of rotation to cause the inflow of the liquid through the inflow structure to the radially inner portion of the porous medium and to direct the liquid through the porous medium,
• wherein providing the fluidic module comprises providing a fluidic module, wherein the inflow structure comprises an inflow chamber and a flow resistance channel fluidically connecting the inflow chamber to the fluid chamber, the inflow chamber being filled with a liquid column corresponding to an initial liquid volume, wherein the porous medium and the flow resistance channel are configured to satisfy the following equation:
• D
• =
• r
• 2
• 2
• -
• r
• i
• 2
• 2
• *
• C
• R
• ⁢
• l
• C
• ⁢
• h
• A
• C
• ⁢
• h
• 2
• *
• r
• i
• ⁢
• n
• ,
• m
• *
• A
• m
• *
• k
• wherein
• D is a design factor,
• CR is a geometry factor for calculating the fluidic resistance in the flow resistance channel, that depends on the cross section of the flow resistance channel, wherein the flow resistance channel cross section has a shape that remains the same during said flow,
• Ich is the length of the flow resistance channel,
• Ach is the cross-sectional area of the flow resistance channel,
• rin,m is the radial distance between the radially inner portion of the porous medium and the center of rotation,
• Am is the cross-sectional area of the porous medium perpendicular to the flow, and
• κ is the permeability of the porous medium.