  We developed a new approach comprised of different visualizations for the
comparative spatio-temporal analysis of displacement processes in porous media.
We aim to analyze and compare ensemble datasets from experiments to gain
insight into the influence of different parameters on fluid flow. To capture
the displacement of a defending fluid by an invading fluid, we first condense
an input image series to a single time map. From this map, we generate a
spatio-temporal flow graph covering the whole process. This graph is further
simplified to only reflect topological changes in the movement of the invading
fluid. Our interactive tools allow the visual analysis of these processes by
visualizing the graph structure and the context of the experimental setup, as
well as by providing charts for multiple metrics. We apply our approach to
analyze and compare ensemble datasets jointly with domain experts, where we
vary either fluid properties or the solid structure of the porous medium. We
finally report the generated insights from the domain experts and discuss our
contribution's advantages, generality, and limitations.
