The motion of calcium alginate spheres in a liquid-solid fluidized bed is examined by radioactive particle tracking (RPT) and simulated by computational fluid dynamics coupled with discrete element method (CFD-DEM). Observables relevant for phenomenological models of the solid motion determined from RPT are compared with those arising from the CFD-DEM simulations. Bed expansion, solid distribution, time averaged velocity fields and axial dispersion coefficients calculated from simulations reasonably agree with the experimental values. The influence of the liquid inlet distribution on simulations results is examined. A non-negligible effect is observed on the predicted velocity profiles, solid distribution and dispersion coefficients, mainly in the entrance region. Uniform liquid distribution at the entrance generally predicts a less steeped profile. When the liquid inlet distribution is parameterized considering the geometry of the experimental distributor, the fitting of the solid mean axial velocity and solid distribution radial profiles, judged from a sum of squares of relative errors, improves in 90% and 80%, respectively, compared to results obtained when considering a uniform liquid distribution at the entrance.