This thesis is a contribution to research in the field of Large Eddy Simulation (LES) of particle-laden flow with a focus on the effect of unresolved small scale turbulence on suspended particles. The first substantial contribution of this thesis is a detailed quantification of small scale effects in homogeneous isotropic turbulence. The second contribution of this thesis is an analytical and numerical analysis of three commonly used models that describe the effect of subgrid scales on particles: the Approximate Deconvolution Method (ADM) and two stochastic models. The third contribution is a...