Fakultät Informatik

Turbulence Visualization at the Terascale on Desktop PCs

 Marc Treib*,  Kai Bürger*,  Florian Reichl*,
 Charles Meneveau+ Alex Szalay+, Rüdiger Westermann*

* Technische Universität München, Germany.
+ Johns Hopkins University, Baltimore, Maryland, USA.

Background

Despite the ongoing efforts in turbulence research, the universal properties of the turbulence small-scale structure and the relationships between small- and large-scale turbulent motions are not yet fully understood. The visually guided exploration of turbulence features, including the interactive selection and simultaneous visualization of multiple features, can further progress our understanding of turbulence. Accomplishing this task for flow fields in which the full turbulence spectrum is well resolved is challenging on desktop computers.
This is due to the extreme resolution of such fields, requiring memory and bandwidth capacities going beyond what is currently available. To overcome these limitations, we present a GPU system for feature-based turbulence visualization that works on a compressed flow field representation. We use a wavelet-based compression scheme including run-length and entropy encoding, which can be decoded on the GPU and embedded into brick-based volume ray-casting. This enables a drastic reduction of the data to be streamed from disk to GPU memory. Our system derives turbulence properties directly from the velocity gradient tensor, and it either renders these properties in turn or generates and renders scalar feature volumes. The quality and efficiency of the system is demonstrated in the visualization of two unsteady turbulence simulations, each comprising a spatio-temporal resolution of 10244. On a desktop computer, the system can visualize each time step in 5 seconds, and it achieves about three times this rate for the visualization of a scalar feature volume.

A preprint of the article is available for download below; the definitive version is available  here.

The turbulence data sets used in this publication are courtesy of the  JHU Turbulence Database.

The source code of our GPU compression library, written in C++ and CUDA, is available here. This does NOT include the turbulence visualization system, it only contains the compression code!
Some test data is available separately  here.
Update: The newest version of the code is now  available on Github.

Acknowledgments

This publication is based on work supported by Award No. UK-C0020, made by King Abdullah University of Science and Technology (KAUST).

 

Submission Video

Turbulence Visualizations

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Direct volume rendering of enstrophy production E.
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Two semi-transparent iso-surfaces of QHunt.
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Fine-scale iso-surfaces (gray) and coarse-scale iso-surfaces colored by vorticity direction.
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Multi-scale turbulence analysis in a “focus+context” manner. Iso-surfaces in the fine-scale data (red) are extracted only within iso-surfaces of the coarse-scale version.