Mass-flux fraction


The mass-flux fraction is the ratio of mass-flux of a particular chemical species to the total mass flux of a gaseous mixture. It includes both the convectional mass flux and the diffusional mass flux. It was introduced by Joseph O. Hirschfelder and :de:Charles Francis Curtiss|Charles F. Curtiss in 1948 and later by Theodore von Kármán and Sol Penner in 1954. The mass-flux fraction of a species i is defined as
where
It satisfies the identity
similar to mass fraction, but, the mass-flux fraction can take both positive and negative values. This variable is used in steady, one-dimensional combustion problems in place of mass fraction. For one-dimensional steady flows, the conservation equation for the mass-flux fraction reduces to
where is the mass production rate of species i.