We discuss two typical problems involved in particle resuspension phenomena. First, we analyze the onset of movement of a grain deposited on a surface prior to its possible resuspension. In this case, we look for the critical frequency and amplitude needed for starting the movement of the grain when the surface is perturbed by a sinusoidal vertical vibration. We compare results coming from our own experiments and DEM simulations. The agreement is good and allows evaluating the effect of the relative size of the grain on the initiation of movement. The second problem refers to the resuspension of grains, also deposited on a monolayer surface without interactions between them, due to the effect of aerodynamic forces. The detachment of grains as the wind intensity increases is studied through Monte Carlo simulations and the results are compared with experiments belonging to other authors. The role of the particle rolling mechanisms and the reduction factor due to roughness are discussed. Comparison of numerical and experimental data is promising.