Three-dimensional numerical simulations are presented on the motion of large ensembles of deformable particles (up to 1096 in number) in a channel flow at small inertia. Particles are modeled as capsules, that is, liquid drops surrounded by elastic membranes. Unlike liquid drops where the fluid-fluid interface is characterized by isotropic surface tension, that of a capsule is governed by more complex constitutive laws. Here we assume that the capsule membrane follows the neo-Hookean constitutive law. The particle volume fraction considered is up to 29%. The numerical methodology is based on a mixed finite-difference/Fourier transform method for the flow solver and a front-tracking method for fluid/membrane interaction. In the simulations, the flow field is resolved using up to 288X288X288 grid points, and each particle surface is resolved by 1280 triangular elements. The simulations are computation- and data-intensive, and the first of their kind in the context of deformable capsule suspension. The database generated from the simulations provides a wealth of information on the dynamics of semi-dense suspension of liquid capsules, in particular, and of deformable particles, in general. Preliminary results on flow visualization, particle trajectory, deformation, mean velocity and suspension viscosity are presented.