Simulation of nanofibrous filters produced by the electrospinning method: 1. Pressure drop and deposition of nanoparticles

The peculiarities of the hydrodynamic flow field and diffusion deposition of nanoparticles in filtration layers of nanofibers obtained by spraying a polymer solution in an electric field are considered. The main attention is focused on the effect of doubled nanofibers or pairs of parallel fibers that result from longitudinal splitting of charged jets on the hydrodynamic characteristics. The calculations are performed for a periodical row of doubled parallel fibers oriented normal to the flow. The flow field and the rate of nanoparticle deposition in the row are investigated as dependences on the distances between the pairs of the fibers, interfiber distances in pairs, orientation of the pairs relative to the direction of a flow, and the relations between fiber diameters in the pairs. The equations for the flow of a viscous incompressible liquid are solved under the Stokes approximation employing the method of fundamental solutions, and the stream functions, fields of velocities, and drag forces acting upon the fibers are determined. For the found flow fields, the coefficients of diffusion capture are determined by the numerical solution of the convective diffusion equation. It is established that, when fibers are drawn together in pairs to their contact in a rarefied row, the drag force decreases twofold. This result agrees with experimental data and the analytical solution for the constrained flow around pairs of similar fibers in a rarefied row.