The transverse flow of a viscous incompressible fluid at low Reynolds numbers in model fibrous filters - rows of parallel cylinders - is studied. Single rows of porous and composite cylinders (cylinders with porous shells) are considered as simplest models for novel filters consisting of porous fibers and fibers covered with porous layers. The obtained flow field is used to estimate the efficiency of diffusional deposition of sub-micron aerosol particles upon porous and composite cylinders as a function of Peclet number, permeability of porous material and the distance between cylinders. Also considered are three-dimensional model filters consisting of parallel cylinder rows arranged perpendicularly to the flow and to each other. (c) 2007 Elsevier B.V. All rights reserved.