On the Way Towards Topology-Based Visualization of Unsteady Flow – the State of the Art

Vector fields are a common concept for the representation of many different kinds of flow phenomena in science and engineering.Methods based on vector field topology have shown their convenience for visualizing and analyzing steady flow but a counterpart for unsteady flow is still missing. However, a lot of good and relevant work has been done aiming at such a solution. We give an overview of the research done on the way towards topology-based and -inspired visualization of unsteady flow, pointing out the different approaches and methodologies involved as well as their relation to each other, taking classical (i.e. steady) vector field topology as our starting point. Particularly, we focus on Lagrangian methods, space-time domain approaches, local methods, and stochastic and multi-field approaches. Furthermore, we illustrated our review with practical examples for the different approaches.