The use of pressure drop measurements for estimating ventilation and paper porosity/Verwendung von Zugwiderstandsmesswerten zur Abschätzung von Ventilation und Papierporosität

In our recent article on the above-mentioned topic, the derivation of the pressure drop equations was based on the first approximation that diluting air flow is constant over the length of a filter or tobacco column. While this is a reasonable approximation for filters and tobacco columns with low levels of dilution, it appears to give inaccurate results for tobacco columns with high levels of dilution, as was pointed out by Cummings.