mobile-phase velocity, \(u\)

in chromatography
https://doi.org/10.1351/goldbook.M03954
The linear velocity of the mobile phase across the average cross-section of the chromatographic bed or column.
Source:
PAC, 1993, 65, 819. (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 840 [Terms] [Paper]