This article presents a numerical methodology for capturing air-borne particles by fibrous filter media under collision effect. It reports on the effects of collision and adhesion parameters on particle bounce and re-entrainment phenomena. Hamaker adhesion model in conjunction with particle rebound parameter was assessed for particle capture efficiency and validated with analytical and experimental data. The numerical results were found to be in good agreement with the experimental data. The roles of particle size, media structure and flow velocity in deciding the particle bounce and particle penetration through the filter media were examined. It was found that the particles of greater than 2 tun diameter predominantly bounced and penetrated through the filter media. Three sets of fibrous structure with different solid volume fractions were generated and investigated for particle penetration. It was observed that the particle penetration was due to particle bounce along with significant particle re-entrainment and this was mainly dependent on packing density of the filter media. The structure of fibrous filter media, showing the most significant particle bounce, was identified and the effect of filtration velocity on particle bounce of this structure was discussed.