Knudson number

Therefore, it is necessary to establish the thermodynanuc flow regime in a specimen while analyzing the gas flow through fibrous media. This can be done by calculating an empirical parameter known as the Knudson number Kn, which is defined as the ratio of the gas mean-free path to the fiber radius and is expressed mathematically as shown by Eqn (8.4). 

As discussed in Section 8.1.5, the primary step for modeling the gas flow through nonwoven nanofiber mats is the establishment of a fluid flow regime. The fluid flow regime is determined by calculating the Knudson number (K ), which is defined as the ratio of gas-free mean path to nanofiber radius as expressed in Eqn (8.4). The values of K, in four different ranges, namely, ilCn < 10 , 10 < K < 0.25,0.25 < < 10,... 

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