We present direct simulations with interface resolution of dense, fluidized solidliquid suspensions. The flow of interstitial fluid is solved by the lattice-Boltzmann method (LBM). The monodisperse, spherical particles move under the influence of gravity, hydrodynamic forces stemming from the LBM, subgrid-scale lubrication forces, and hard-sphere collisions. The cases we study have been derived from the experimental work by Duru et al. . We first show that the experimentally observed waves are well represented by the simulations. Subsequently we use the detailed information contained in the simulation results to assess two-fluid closures, with a focus on the role of compaction and dilation of the particle phase.