[Forschungsseminar-BSV] Forschungsseminar Computergrafik, Bildverarbeitung und Visualisierung

[Patrick Oesterling]

A C H T U N G: Bitte beachten Sie den von der üblichen Startzeit und vom 
üblichen Veranstaltungsort abweichenden Beginn dieses Forschungsseminars!

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E I N L A D U N G

zum Forschungsseminar 'Computergrafik, Bildverarbeitung und 
Visualisierung' am Dienstag, den 02. September 2014, 13:15 Uhr, Raum 
A-314 im Augusteum am Augustusplatz.


Wir hören einen Vortrag von:


Stephan Hellmich
Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) in der 
Helmholtzgemeinschaft
Institut für Planetenforschung

mit dem Titel

"cuSwift - A suite of numerical integration methods for modelling 
planetary systems implemented in C/CUDA"


zum Inhalt:

Simulations of dynamical processes in planetary systems represent an 
important tool for studying their orbital evolution [1][6][4]. Using 
modern numerical integration methods, it is possible to model systems 
containing many thousands of objects over time scales of several hundred 
million years. However, in general supercomputers are needed to get 
reasonable simulation results in acceptable execution times [4]. To 
exploit the ever growing computation power of Graphics Processing Units 
(GPUs) in modern desktop computers we implemented cuSwift, a library of 
numerical integration methods for studying long- term dynamical 
processes in planetary systems. cuSwift can be seen as a 
re-implementation of the famous SWIFT integrator package written by Hal 
Levison and Martin Duncan. cuSwift is written in C/CUDA and contains 
different integration methods for various purposes. So far, we have 
implemented three algorithms: a 15th order Radau integrator [3], the 
Wisdom-Holman Mapping (WHM) integrator [7] and the Regularized Mixed 
Variable Symplectic (RMVS) Method [5]. These algorithms treat only the 
planets as mutually gravitationally interacting bodies whereas asteroids 
and comets (or other minor bodies of interest) are treated as massless 
test particles which are gravitationally influenced by the massive 
bodies but do not affect each other or the massive bodies. The main 
focus of this work is on the symplectic methods (WHM and RMVS) which use 
a larger time step and thus are capable of integrating many particles 
over a large time span. As an additional feature, we implemented the 
non-gravitational Yarkovsky effect as described by M. Brož [2]. With 
cuSwift we show that the use of modern GPUs makes it possible to speed 
up these methods by more than one order of magnitude compared to the 
single-core CPU implementation, thereby enabling modest workstation 
computers to perform long-term dynamical simulations. We use these 
methods to study the influence of the Yarkovsky effect on resonant 
asteroids. We present first results and compare them with integrations 
done with the original algorithms implemented in SWIFT in order to 
assess the numerical precision of cuSwift and to demonstrate the speedup 
we achieved using the GPU.


References:
[1]W. Bottke, “Debiased Orbital and Absolute Magnitude Distribution of 
the Near-Earth Objects,” Icarus, vol. 156, no. 2, pp. 399–433, 2002.
[2]M. Brož, “Yarkovsky Effect and the Dynamics of the Solar System,” 
Charles University, Faculty of Mathematics and Physics Astronomical 
Institute, Praha, 2006.
[3]E. Everhart, “An efficient Integrator that uses Gauss-Radau 
Spacings,” in Dynamics of Comets: Their Origin and Evolution, vol. 115, 
Springer Netherlands, 1985, pp. 185–202.
[4]S. Greenstreet, H. Ngo, and B. Gladman, “The orbital distribution of 
Near-Earth Objects inside Earth’s orbit,” Icarus, vol. 217, no. 1, pp. 
355–366, 2012.
[5]H. F. Levison and M. J. Duncan, “The Long-term Dynamical Behavior of 
Short-Period Comets,” Icarus, vol. 108, no. 1, pp. 18–36, 1994.
[6]A. Morbidelli, R. Brasser, R. Gomes, H. F. Levison, and K. Tsiganis, 
“Evidence from the asteroid belt for a violent past evolution of 
Jupiter’s orbit,” The Astronomical Journal, vol. 140, no. 5, pp. 
1391–1401, 2010.
[7]J. Wisdom and M. Holman, “Symplectic maps for the n-body problem,” 
The Astronomical Journal, vol. 102, p. 1528, 1991.



Alle Interessierten sind im Namen von Professor Dr. Scheuermann herzlich 
eingeladen.

Mit freundlichen Grüßen,
Patrick Oesterling