  Even though the analysis of unsteady 2D flow fields is challenging, fluid
mechanics experts generally have an intuition on where in the simulation domain
specific features are expected. Using this intuition, showing similar regions
enables the user to discover flow patterns within the simulation data. When
focusing on similarity, a solid mathematical framework for a specific flow
pattern is not required. We propose a technique that visualizes similar and
dissimilar regions with respect to a region selected by the user. Using
infinitesimal strain theory, we capture the strain and rotation progression and
therefore the dynamics of fluid parcels along pathlines, which we encode as
distributions. We then apply the Jensen-Shannon divergence to compute the
(dis)similarity between pathline dynamics originating in a user-defined flow
region and the pathline dynamics of the flow field. We validate our method by
applying it to two simulation datasets of two-dimensional unsteady flows. Our
results show that our approach is suitable for analyzing the similarity of
time-dependent flow fields.
