VIRACOCHA: An Efficient Parallelization Framework for Large-Scale CFD Post-Processing in Virtual Environments

ABSTRACT

One recommended strategy for the analysis of CFD-data is the interactive exploration within virtual environments. Common visualization systems are unable to process large data sets while carrying out real-time interaction and visualization at the same time. The obvious idea is to decouple flow feature extraction from visualization. This paper covers the functionality of the parallel CFD post-processing toolkit Viracocha. Two aspects are discussed in more detail. The first approach covers strategies to reduce the loading time. Data caching and prefetching are employed to reduce access time. The second aspect concerns an approach called streaming that minimizes the time a user has to wait for first results. Viracocha already sends coarse intermediate data back to the virtual environment before the final result is available. Different streaming and data handling strategies are described. In order to emphasize the benefit of our implementation efforts, some strategies are applied to multi-block CFD data sets.

REFERENCES

• 1: Andries van Dam , Andrew S. Forsberg , David H. Laidlaw , Joseph J. LaViola , Rosemary M. Simpson, Immersive VR for Scientific Visualization: A Progress Report, IEEE Computer Graphics and Applications, v.20 n.6, p.26-52, November 2000 [doi>10.1109/38.888006]
• 2: Steve Bryson, Virtual reality in scientific visualization, Communications of the ACM, v.39 n.5, p.62-71, May 1996 [doi>10.1145/229459.229467]
• 3: [3] Oliver Kreylos, Wes Bethel, Terry J. Ligocki, Bernd Hamann, "Virtual-Reality-Based Interactive Exploration of Multiresolution Data", Springer Verlag, Heidelberg, pp. 205 -224, 2001.
• 4: Steve Bryson , Creon Levit, The virtual windtunnel: an environment for the exploration of three-dimensional unsteady flows, Proceedings of the 2nd conference on Visualization '91, October 22-25, 1991, San Diego, California
• 5: S. Bryson , M. Gerald-Yamasaki, The distributed virtual windtunnel, Proceedings of the 1992 ACM/IEEE conference on Supercomputing, p.275-284, November 16-20, 1992, Minneapolis, Minnesota, United States
• 6: [6] D. Rantzau, K. Frank, U. Lang, D. Rainer, U. Wössner, "COVISE in the CUBE: an Environment for Analyzing Large and Complex Simulation Data", Proceedings, 2nd Workshop on Immersive Projection Technology (IPT98), Ames, Iowa, 1998.
• 7: Tahsin Kurc , Ümit Çatalyürek , Chialin Chang , Alan Sussman , Joel Saltz, Visualization of Large Data Sets with the Active Data Repository, IEEE Computer Graphics and Applications, v.21 n.4, p.24-33, July 2001 [doi>10.1109/38.933521]
• 8: Stephan Olbrich , Helmut Pralle , S. Raasch, Using Streaming and Parallelization Techniques for 3D Visualization in a High-Performance Computing and Networking Environment, Proceedings of the 9th International Conference on High-Performance Computing and Networking, p.231-240, June 25-27, 2001
• 9: [9] T. van Reimersdahl, T. Kuhlen, A. Gerndt, J. Henrichs, C. Bischof, "ViSTA: a Multimodal, Platform-Independent VR-Toolkit Based on WTK, VTK, and MPI", Proceedings, 4th International Immersive Projection Technology Workshop, Ames, Iowa, 2000.
• 10: M. Schirski , A. Gerndt , T. van Reimersdahl , T. Kuhlen , P. Adomeit , O. Lang , S. Pischinger , C. Bischof, ViSTA FlowLib - framework for interactive visualization and exploration of unsteady flows in virtual environments, Proceedings of the workshop on Virtual environments 2003, p.77-85, May 22-23, 2003, Zurich, Switzerland [doi>10.1145/769953.769963]
• 11: [11] W. Schroeder (ed.), "The VTK User's Guide", Kitware Inc., 2001.
• 12: [12] J. Ahrens, C. Law, W. Schroeder, K. Martin, and M. Papka, "A Parallel Approach for Efficiently Visualizing Extremely Large, Time-Varying Datasets", Technical Report #LAUR- 00-1620, Los Alamos National Laboratory, 2000.
• 13: Andreas Gerndt , Mark Asbach , Torsten Kuhlen , Christian Bischof , Stefan Lankes , Thomas Bemmerl, Conceptual design and implementation of a pipeline-based VR-system parallelized by CORBA, and comparison with existing approaches, Proceedings of the 2004 ACM SIGGRAPH international conference on Virtual Reality continuum and its applications in industry, June 16-18, 2004, Singapore [doi>10.1145/1044588.1044669]
• 14: [14] A. Gerndt, T. van Reimersdahl, T. Kuhlen, J. Henrichs, C. Bischof, "A Parallel Approach for VR-based Visualization of CFD Data with PC Clusters", Proceedings, 16th IMACS World Congress, Lausanne, Switzerland, 2000.
• 15: [15] A. Gerndt, M. Schirski, T. Kuhlen, C. Bischof, "Parallel Calculation of Accurate Path Lines using Multi-Block CFD Datasets with Changing Geometry", in: Hamid R. Arabnia, Youngsong Mun (eds.): Proceedings of the International Conference on Parallel and Distributed Processing Techniques and Application, PDPTA'03, Las Vegas, Nevada, USA, pp. 1298-1304, 2003.
• 16: William Gropp , Ewing Lusk , Anthony Skjellum, Using MPI (2nd ed.): portable parallel programming with the message-passing interface, MIT Press, Cambridge, MA, 1999
• 17: [17] Cláudio T. Silva, Yi-Jen Chiang, Jihad El-Sana, Peter Lindstrom, "Out-Of-Core Algorithms for Scientific Visualization and Computer Graphics", Course Notes, IEEE Visualization 2002, Boston, Massachusetts, October 2002.
• 18: John T. Robinson , Murthy V. Devarakonda, Data cache management using frequency-based replacement, Proceedings of the 1990 ACM SIGMETRICS conference on Measurement and modeling of computer systems, p.134-142, April 1990, Univ. of Colorado, Boulder, Colorado, United States
• 19: [19] A. Abdelfattah, "Numerische Simulation von Strömungen in 2-und 4-Ventil-Motoren", PhD thesis, Aachen University, Shaker Verlag, Aachen, 1998.
• 20: [20] Zhiyan Liu, Adam Finkelstein, Kai Li, "Progressive View-Dependent Isosurface Propagation", Proceedings, IEEE TCVG Symposium on Visualization, VisSym 2001, Mai 2001.
• 21: Jinzhu Gao , Han-Wei Shen, Parallel view-dependent isosurface extraction using multi-pass occlusion culling, Proceedings of the IEEE 2001 symposium on parallel and large-data visualization and graphics, October 22-23, 2001, San Diego, California
• 22: [22] J. Jeon, F. Hussain. "On Identification of a Vortex", Journal for Fluid Mechanics, Vol. 285, pp. 69-94, 1995.

INDEX TERMS

Keywords:
CFD Post-Processing, Virtual Reality, Parallelization, Caching, Prefetching, Data Streaming, Multi-Resolution