Many flow problems in environmental, technical and biological systems are characterized by a distinct interaction between a flow region in porous-medium and a free-flow region in quasi-one-dimensional hollow structures. In this study, different model concepts, based on a dual-continuum strategy, for the simulation of coupled porous-media flow and (lower-dimensional) pipe flow are further developed and tested. The dual-continuum concept is extended for coupling multi-phase porous-media flow with lower-dimensional single-phase free flow. The complexity of the considered flow regimes is increased gradually. Examples are given for a coupled single-phase incompressible and compressible flow in both porous-media and pipe flow domains. Furthermore, the coupling of single-phase pipe flow with a multi-phase flow based on Richard's equation for the unsaturated soil zone is modeled, where the important role of capillary effects for the mass exchange rate between the two continua could be illustrated. The last example introduces a concept for a two-phase porous-media flow coupled with a single-phase (gas) pipe-flow problem, which revealed that the mobility exchange term can be decisive for the mass exchange rate.