The effect of particles on turbulence is a key phenomenon in many practical industrial flows (slurries, fluidized beds, …). Depending on the size ratio between the particles and the smallest scale of turbulence, the particle feedback on the flow can either enhance or suppress turbulence. In this communication, we will focus on two generic flow configurations: homogeneous isotropic turbulence seeded with particles and a transitional plane channel flow. Fully-coupled numerical simulations are used to investigate the interactions between neutrally-buoyant finite-size particles and the fluid flow. The numerical method chosen for this work is the Force-Coupling Method (FCM) (Climent and Maxey, 2009).