Wall Velocity
Gas transport through very fine channels involves a transition state where the fluid velocity at the solid boundary is not zero. This mechanism, known as slip flow, occurs when the pores in a linen filter or treated fabric are comparable in size to the mean free path of the gas molecules. It results in a higher flow rate than would be predicted by standard fluid dynamics equations.
Rarefaction Effect
Friction between the gas and the fiber surface is reduced because the molecules do not stick to the walls in a traditional stagnant layer. The occurrence of slip flow requires a correction factor to the permeability calculations used for industrial linen fabrics. This adjustment ensures that the pressure drop across a high-efficiency filter is modeled correctly during the design phase.
Permeability Model
Engineers use the Klinkenberg effect to account for the way gas permeability changes with the average pressure. As the pressure drops, the slip flow becomes more significant and the measured permeability appears to increase. For linen mills producing precision filtration media, understanding this relationship is necessary for meeting the technical specifications of global industrial clients.
This correction prevents errors in the predicted performance of the media when it is used in low-pressure or high-altitude environments.
