A three-dimensional (3-D) computational fluid dynamics (CFD) code has been developed to predict flow dynamics and pressure drop characteristics in geometry-modified filters in which the normalized distance of the outlet channel plugs from the inlet has been varied at 0.25, 0.50, and 0.75. In clean filter simulations, the pressure drop in geometry-modified filters showed higher values than for conventional filters because of the significant change in the pressure field formed inside the channel that determines the amount of flow entering the modified channel. This flow through the modified channel depends on plug position initially but has a maximum limit when pressure difference and geometrical change are compromised. For soot loading simulations, a Lagrangian multiphase flow model was used to interpret the hydrodynamics of particle-laden flow with realistic inputs. Such inputs include mass concentration and size distribution of the particulates in the diesel exhaust, which are measured directly from experiments. Pressure drop characteristics in the geometry-modified filter simulations showed promising potential advantages compared with conventional filters. Particle behaviors, in terms of boundary conditions, on each interface of the model were set independently and selectively to represent two main filtration regimes. Their distributions during the early stage of the filtration process are predicted at a 3-D channel scale. Validated model results show agreement with the analytical and experimental results.