reduced mobile phase velocity, v

in chromatography
A term used mainly in liquid chromatography. It compares the mobile phase velocity with the velocity of diffusion into the pores of the particles (the so-called diffusion velocity, u D):
v = u ̄ u D = u ̄ d p D M
In open-tubular chromatography:
v = u ̄ d c D M
PAC, 1993, 65, 819 (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 840