An efficient parallel tree-code for the simulation of self-gravitating systems

Miocchi, P.; Capuzzo-Dolcetta, Roberto

doi:10.1051/0004-6361:20011609

Cited by 25 publications

(28 citation statements)

References 13 publications

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“…As regards the computational techniques, we adopted an N-body representation for the stars in the clusters, simulating their dynamics by means of the parallel ''treeATD'' code (Miocchi & Capuzzo-Dolcetta 2002), whose main features were also described in Paper I.…”

Section: The Simulationsmentioning

confidence: 99%

Merging of Globular Clusters in Inner Galactic Regions. II. Nuclear Star Cluster Formation

Capuzzo–Dolcetta

Miocchi

2008

ApJ

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In this series of papers, we present the results of detailed N-body simulations of the interaction of a sample of four massive globular clusters in the inner region of a triaxial galaxy for two different sets of initial conditions that correspond to different initial density concentrations. A full merging of the clusters takes place, leading to a slowly evolving cluster that is quite similar to observed nuclear clusters. Actually, both the density and the velocity dispersion profiles match qualitatively, and also quantitatively after scaling to a larger number of merger globulars, with the observed features of many nucleated galaxies. In the case of dense initial clusters, the merger remnant shows a density profile more concentrated than that of the progenitors, with a central density higher than the sum of the progenitors' central densities and an effective radius compatible with observed nuclear values. These findings support the idea that a massive nuclear cluster may have formed in the early phases of the mother galaxy's evolution and led to the formation of a nucleus, which in many galaxies has a luminosity profile similar to that of an extended King model. A correlation with galactic nuclear activity is suggested.

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Section: The Simulationsmentioning

confidence: 99%

Merging of Globular Clusters in Inner Galactic Regions. II. Nuclear Star Cluster Formation

Capuzzo–Dolcetta

Miocchi

2008

ApJ

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“…The relative acceleration error is defined as δa/a ≡ |a − a D |/|a D |, here a D is the particle acceleration evaluated in the direct summation limit. The results show that for simulation S2L the relative errors in the forces are always below ∼ 3%, an upper limit which has been found to yield reasonable accuracy in various tests (Davé, Dubinski & Hernquist 1997, Springel, Yoshida & White 2001, Miocchi & Capuzzo-Dolcetta 2002.…”

Section: With 50mentioning

confidence: 62%

“…Another comparison can be made with the parallel treecode developed by Miocchi & Capuzzo-Dolcetta (2002). The authors computed gravity speeds on a CRAY T3E for a Plummer distribution with N p = 128, 000 particles.…”

Section: Scalabilitymentioning

confidence: 99%

Parallelization of a treecode

Valdarnini

2003

New Astronomy

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I describe here the performance of a parallel treecode with individual particle timesteps. The code is based on the Barnes-Hut algorithm and runs cosmological N-body simulations on parallel machines with a distributed memory architecture using the MPI message-passing library. For a configuration with a constant number of particles per processor the scalability of the code was tested up to P = 128 processors on an IBM SP4 machine. In the large P limit the average CPU time per processor necessary for solving the gravitational interactions is ∼ 10% higher than that expected from the ideal scaling relation. The processor domains are determined every large timestep according to a recursive orthogonal bisection, using a weighting scheme which takes into account the total particle computational load within the timestep. The results of the numerical tests show that the load balancing efficiency L of the code is high ( > ∼ 90%) up to P = 32, and decreases to L ∼ 80% when P = 128. In the latter case it is found that some aspects of the code performance are affected by machine hardware, while the proposed weighting scheme can achieve a load balance as high as L ∼ 90% even in the large P limit.

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“…An example of a modern tree code is Bonsai [13] but also BRIDGE [14] which simultaneously takes advantages from both the direct and the tree approach. Another example is TreeATD (tree-code with Adaptive Tree Decomposition) developed by Miocchi and Capuzzo-Dolcetta [15]. Another kind of approximation scheme is that developed by Ahmad and Cohen [16].…”

Section: Introductionmentioning

confidence: 99%

A performance comparison of different graphics processing units running direct N-body simulations

Capuzzo–Dolcetta¹,

Spera²

2013

Computer Physics Communications

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Hybrid computational architectures based on the joint power of Central Processing Units and Graphic Processing Units (GPUs) are becoming popular and powerful hardware tools for a wide range of simulations in biology, chemistry, engineering, physics, etc.. In this paper we present a comparison of performance of various GPUs available on market when applied to the numerical integration of the classic, gravitational, N-body problem. To do this, we developed an OpenCL version of the parallel code (HiGPUs) used for these tests, because this version is the only apt to work on GPUs of different makes. The main general result is that we confirm the reliability, speed and cheapness of GPUs when applied to the examined kind of problems (i.e. when the forces to evaluate are dependent on the mutual distances, as it happens in gravitational physics and molecular dynamics). More specifically, we find that also the cheap GPUs built to be employed just for gaming applications are very performant in terms of computing speed also in scientific applications and, although with some limitations in central memory and in bandwidth, can be a good choice to implement a machine for scientific use at a very good performance to cost ratio.

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An efficient parallel tree-code for the simulation of self-gravitating systems

Cited by 25 publications

References 13 publications

Merging of Globular Clusters in Inner Galactic Regions. II. Nuclear Star Cluster Formation

Merging of Globular Clusters in Inner Galactic Regions. II. Nuclear Star Cluster Formation

Parallelization of a treecode

A performance comparison of different graphics processing units running direct N-body simulations

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