Particle-laden flows in a vertical channel were simulated using Euler-Lagrangian (EL), Eulerian-Eulerian Anisotropic-Gaussian (EE-AG), and Reynolds-averaged Navier-Stokes (RANS) two-fluid model including a Reynolds-stress model (RSM) modeling techniques. Two sets of cases varying the overall mass loading were done using particle sizes corresponding to either a large or small Stokes number. Primary and turbulent statistics extracted from EL and EE-AG simulations were compared and used to inform parameters and closures applied in the RSM. The statistics collected from the small Stokes number particle cases correspond well between the EL and the EE-AG models, including the transition from shear-induced turbulence to relaminarization to cluster-induced turbulence (CIT) as the mass loading increased. The EE-AG model was able to capture the behavior of the EL simulations only at the largest particle concentrations using the large Stokes particles. This is due to the limitations involved with employing a particle-phase Eulerian model to simulate a system that has a low particle number concentration. While the behavior at the center of the channel using the RSM compared well with the other simulations, including the transition from fully-developed turbulent flow to relaminarization to CIT as the mass loading increased, the behavior close to the wall deviated significantly. The primary contributor to this difference was the application of a uniform drag coefficient, which resulted in the RSM overpredicting the fluid-phase turbulent kinetic energy close to the wall. When considering small-Stokes particles, the RSM at greater mass loadings reproduced the transient clustering observed in the other models.