Interception

Interception is a key mechanism in depth filtration and describes the process by which a particle following a streamline comes into contact with a fiber or pore edge and adheres to it. A particle is captured when the distance between its center and the fiber becomes smaller than its radius. Unlike inertial impaction, the particle follows the flow path and is not diverted by mass inertia.

According to the literature, interception occurs when a particle comes close enough to a fiber strand to touch it and is captured through adhesion.

This mechanism is particularly relevant for particles that are larger than the pore radius but have low mass, allowing them to follow the flow. The likelihood of interception increases with the ratio of particle diameter to fiber diameter and with fiber density. In fiber nonwovens, interception works in combination with diffusion and inertial impaction to capture particles across a wide size range.

When designing depth filters, parameters such as fiber diameter, fiber density, and filter thickness are selected to achieve an optimal balance between pressure drop and filtration efficiency.
GKD applies these principles to engineer nonwovens and composite meshes that ensure a high interception rate for target particle sizes while maintaining low flow resistance.