Informatics, TU Vienna

Uses and Misuses of Topology in Numerical Flow Visualization

Numerical flow visualization is gaining importance because of the continuing trend from experiments toward computational fluid dynamics.

Abstract

Numerical flow visualization is gaining importance because of the continuing trend from experiments toward computational fluid dynamics. We have come to the situation where reliable numerical data are easily available but often hard to interpret because their size and intricacy challenge current visualization tools. The state of the art in flow visualization is advancing on several fronts, an important one being the field of feature-based visualization, which aims at revealing flow features such as vortices, flow separation, or recirculation. Such flow phenomena are of interest because of their effect, either beneficial or adverse, in industrial applications like power generation, mixing, or combustion. Feature-based flow visualization again splits into several branches, but one of them has become particularly popular under the name of vector field topology. In this talk we present work in topology-based flow visualization, resulting from our collaboration with turbomachinery companies and focusing on the optimization of water turbines. We discuss the usage of vector field topology for extracting the above mentioned flow features, and additional ones such as vortex rings and vortex breakdown bubbles. We address the limitations of vector field topology and the current search for an adequate extension to unsteady flow fields. Finally we move to the field of Lagrangian coherent structures, which can be interpreted as a time-dependent variant of vector field topology. There, we present a technique for accelerating their computation, based on adaptive mesh refinement.

Biography

Ronald Peikert is a Titularprofessor (honorary professor) in the Institute of Computational Science at ETH Zurich. He received his diploma in mathematics in 1979 and his Ph.D. in mathematics in 1985, both from ETH Zurich. He spent the year 1986 as a visiting assistant professor at the University of Minnesota. Back at ETH, we worked for two years as a senior assistant at the Mathematical Seminar, for six years as the head of the graphics group of the Interdisciplinary Project Center for Supercomputing, and for three years as the head of the scientific visualization group of the Swiss Center of Scientific Computing. Since 1999 he is a senior researcher in the Computer Graphics Laboratory of ETH. Ronald Peikert is a member of the steering committee of the EuroVis symposium. His research interests include flow visualization, feature extraction techniques, and industrial applications of visualization.