The Distribution of the Air Flow through a Cigarette / Die Verteilung des Ventilationsstromes auf einer Cigarette

The distribution of the air flow through the porous wrapping of a cigarette is

ν (λ, l) being the density of the air flow (cm³ sec^-1 cm^-1) on the paper wrapping at the position l if l is the length of the porous paper wrapping between the non-porous tip and the burning cone and l is the distance of the position in question from the non-porous tip. ν (λ, l) is given in air flow per cm rather than in air flow per cm² because of the cylindrical shape of the cigarette. I denotes the total stream at the mouth piece, a is the specific conductivity to air flow of the paper wrapping, b is the specific resistance to air flow of the tobacco rod, R_G is the resistance to air flow of the burning cone [compare (1)]. The formula is derived and discussed. The dependence of the distribution of the ventilation stream on the length l and on the resistance RG is demonstrated for the case of a formerly investigated cigarette rod (1). The gradient of ν (λ, l) is

so that the density of the ventilation stream through the paper wrapping decreases almost linearly from its maximum at the tip to its minimum at the burning cone if the degree of ventilation is low, i.e. if the air flow I (λ, l) in the cigarette is not much higher at λ = 0 than at λ = l