The modeling of the pressure drop and particle performance of fibrous filter media is a challenging research area. Numerous approaches and models have been developed over the years with each having strengths and weaknesses. These models can be grouped into 4 primary types: single fiber, empirical, statistical, and computational. Aspects of the single fiber and computational models are presented here.
Single fiber models use the performance characteristics of an individual fiber to predict the performance of the entire fibrous structure. Such models are easily implemented with simple programs or they can be built into a spreadsheet. The single fiber models are useful for directional insight into the impact of fiber size and bulk media structure. However, the random nature of non-woven fiber structures is not well accounted for in single fiber models.
New computational methods and increased computer speed allow for direct simulation of fibrous structures. Directly measured fiber topography or computer generated structures can be modeled. These models simulate both the flow and the particle capture in the media. The new methods show much promise for providing detailed analysis of fiber mat. Currently, the models are being validated and are computational expensive to run, but they are rapidly becoming a more accessible tool for design.