We investigate a partitioned coupling scheme applied to a system of free flow over a porous medium. The coupling scheme follows a partitioned approach which means that the flow fields in the two domains are solved separately and information is exchanged over the sharp interface that separates the free-flow and the porous-medium domain. Technically, the coupling is realized via the open-source library preCICE, employing a pure black-box approach such that different solver frameworks can be used with highly specialized solvers in each of the flow domains. We investigate the partitioned coupling approach numerically by comparing it to a monolithic coupling scheme with respect to convergence and accuracy. This is the first time a partitioned black-box coupling is used for coupling free flow and porous-media flow. The coupling approach is numerically validated and different partitioned coupling approaches are compared with each other.