Modeling numerically Flow-Induced Vibrations in heat exchangers at a microscopic scalerequires high computational resources and time which are still unreachable. Thereforemodel reduction is investigated in the present work in order to address the issue ofsimulation computational time reduction. In the framework of POD-Galerkin projectionmethods, the purpose is to propose optimal a posteriori reduction strategies enabling errorcontrol on approximation as well as Reduced-Order Model (ROM) interpolation to dealwith sensitivity analysis of solutions to parameter perturbations. A multi-phase fluid–solidPOD-Galerkin-based method is proposed for modeling flows and vibrations in cylinderarrangements under single-phase fluid cross-flows. Moreover a single-POD basis method isevaluated in the context of ROM interpolation. This work is a first step in the developmentof robust ROM describing fluid and solid dynamics in the presence of turbulence, heattransfer effects and large magnitude structure displacements and deformations