burning velocity, \(\nu_{\text{b}}\)

of a flame front, in flame emission and absorption spectrometry
https://doi.org/10.1351/goldbook.B00762
The mean velocity of the flame front (in \(\text{mm s}^{-1}\)) towards the unburnt gas mixture (usually vertically downwards). The quantity applies to gas mixtures and not to injection burners, and depends on the flame temperature and the solvent nebulized.
Source:
PAC, 1986, 58, 1737. (Quantities and units in clinical chemistry: Nebulizer and flame properties in flame emission and absorption spectrometry (Recommendations 1986)) on page 1742 [Terms] [Paper]