Dynamics in dense stellar clusters: Binary black holes
in galactic centers

M. Hemsendorf, R. Spurzem, D. Merritt
1. Binary black holes in galaxies
2. Point mass dynamics
3. Parallelizing strategies
4. The results

Black holes in galactic centres

Why binaries?

What do you need for simulating such a system?

How can you win against the N2 scaling?

The systolic algorithm

A method for circular contraction of a distributed quantity is often called a systolic algorithm. The figure below shows a communication pattern which makes use of nonblocking communication. This pattern resembles a systolic algorithm: The data is distributed evenly to all processing nodes, there are no redundant data. While computing the forces on a set of positions, this set is sent using nonblocking communication to the neighbouring processor. The partial sum of the force calculation follows on the next shift cycle. The load balance is perfect as long the communication time is shorter than the computing time. In a direct force computation this can always be accomplished by choosing a large enough problem size.

Other routing mechanisms

Finally results:

Summary:

Acknowledgements

This project is funded by Deutsche Forschungsgemeinschaft (DFG) project Sp 345/9-1 and SFB 439 at the University of Heidelberg and NSF grant AST 00-71099, NASA grants NAG 5-7019, NAG 5-6037, and NAG 5-9046 at Rutgers, the State University of New Jersey.

Technical help and computer resources are provided by NIC in Jülich, HLRS in Stuttgart, EPCC in Edinburgh, ZIB in Berlin, SSC in Karlsruhe, the Pittsburgh Supercomputer Center, the NASA Center for Computational Sciences (NCCS), the San Diego Supercomputer Center (SDCS), and the National Partnership for Advanced Computational Infrastructure (NPACI), Rutgers University, University of Heidelberg, and University of Kiel.

Contact: marchems@physics.rutgers.edu

Marc Hemsendorf
Mon May 21 01:18:10 MEST 2001