This paper describes an Eulerian approach for partitioned fluid–structure simulations based on a fluid solver using regularly and adaptively refined Cartesian grids. The particular focus is on the efficient implementation and embedding of the fluid solver in the context of coupled simulations. Special subjects are the efficient layout of data structures and data access based on space-filling curves and the realisation of geometry and topology changes. In addition, a coupling environment is presented that allows for an easy and flexible coupling of flow and structure codes. Simulation results are provided for large particle movements within the drift ratchet scenario.