The results of calculations of two- and three-dimensional flows on blocked grid domains consist of vast data collections with a simple, regular structure. The inspection of these results can only be done efficiently by graphical means, and by exploiting the regular structure of the data. There is a large similarity between the format of the results of the different flow-calculation programs (flow solvers). Therefore it is possible to have one graphical visualization system (set of programs) for all the flow solvers. In this report a conceptual design for such a visualization system is presented. An important part of this design is the structure of the interface between solvers and visualizer, as this file is the interface between various flow solvers and one visualization system.