The interaction of flows and solid objects is a recurring problem in several engineering disciplines. The objective of this work is to present a fully coupled model, based on the fundamental conservation laws of hydrodynamics, namely the continuity and Navier-Stokes equations, and the equation of conservation of momentum of solid bodies. The coupled numerical solution, based on Smoothed Particle Hydrodynamics (SPH) and Discrete Element Method (DEM) discretization, resolves solid-solid and solid-fluid inter-actions in broad range of scales, from details of momentum transfer at solid boundaries to large scales typical of engineering problems, such as transport of debris or hydrodynamic actions on structures. The implementation is done and optimized for the GPU architec-ture, combined with a MPI implementation allowing for multi-GPU processing. This takes full advantage of the massive throughput of each machine, while advanced multi-criteria dynamic loading keeps the simulation load optimal. A general overview of the methods and the coupling is addressed, and results for complex multiphasic flows are shown.