Nanofiber media have shown great potential as a filtration material, both for surface and depth filtration, outperforming traditional fibers in energy efficiency and filtration performance. Due to their large specific surface area by volume, nanofibers significantly increase the chances for smallest aerosol particles to adhere to the fiber surfaces, thereby achieving high filtration efficiency for particles of the Most Penetrating Particle Size (MPPS) at minimal pressure loss.

The deposition behavior of submicron particles on nanofiber structures remains an active area of research. Understanding this phenomenon is crucial for optimizing the performance of nanofiber filter media, such as enhancing their dust holding capacity while minimizing pressure loss across the filter.

In previous numerical studies, numerous authors modelled particle deposition on nanofibers based on the assumption that a particle predicted to collide with a fiber or an already deposited particle will adhere to the fiber/particle (so called "stick-on-first contact" model). For submicron-size particles, this assumption, i.e., no particle rebound upon initial contact might be acceptable. However, the assumption of "frozen deposition", which neglects the movement, dynamics and interaction of the deposited particles, is not able to accurately predict the formation of particle dendrites or agglomerates [1][2].

Once a sufficient number of particles has been deposited, detachment of particulate aggregates or agglomerates can occur, even in the case of submicron-size particles [1][3][4]. While this phenomenon is difficult to observe experimentally, it can be studied by means of numerical simulations using a calibrated set of DEM model parameters while resolving the flowfield around each particle.

Accordingly, the present investigation employs a four-way coupled and fully resolved CFD-DEM simulation methodology based on the Immersed-Boundary (IB) method, to investigate the deposition of submicron-size particles on a representative nanofiber structure while allowing for detachment and re-entrainment of particles and particle agglomerates. Figure 1 depicts initial simulation results reveal different phases of the deposition process, i.e., initial deposition of particles on bare fiber (Fig. 1A), formation of particles agglomerates (Fig. 1B), and bridging between these agglomerates (Fig. 1C), eventually leading to clogging of the filter medium...

Crossing of the nanofibers plays a crucial role in the observed “bridging” phenomena between deposited particle structures. The particle bridges act similarly to individual nanofibers by providing additional surface area for further particle deposition. This phenomenon can significantly influence ...