The definitions provided here are derived from two manuscripts:
G. Deininger, Strömungvorgänge in Säulen und ihre Bedeutung in der Säulenchromatographie,
Ber. Bunsengesellschaft für physikalische Chemie, 77, 145 (1973).
C.A. Cramers, J.A. Rijks, J.P.M. Schutjes, Factors determining flow rate in chromatographic columns,
Chromatographia, 14, 439-444, (1981).
In chemical engineering the solvent velocity is defined as (lhs in equation 2.2). This is called the superficial velocity.
F is the volumetric flow rate through the column and A the cross sectional surface of the empty column. In equation 2.2, Ko is called "specific permeability". This formulation is also known as Darcy's law.
However other definitions of solvent velocity are used in this context and need to be explained.