The clogging mechanism has attracted increasing attention due to widespread applications of fibrous filtration in the industry. We carry out computational fluid dynamics with a discrete element method to investigate the clogging in a two-fiber system. The role of interparticle adhesion among microparticles in the unclogging-clogging transition is examined. A clogging phase diagram in the form of the Stokes number and the adhesion parameter (Ad) is built. We show that the formation of clogs contains two sequential processes, the growth of particle chain and the formation of bridges connecting two fibers. A stronger adhesion results in a longer growing time but a shorter bridging time of particle chains. These competing trends yield an "optimal" Ad range with the fewest penetrating particles. The structural analysis of the clogs shows that as Ad increases, the average local volume fraction and coordination number decrease. The reconstruction of particles mainly happens in the initial cake filtration stage. (C) 2019 Elsevier B.V. All rights reserved.