15 research outputs found
GPU-Enabled Particle-Particle Particle-Tree Scheme for Simulating Dense Stellar Cluster System
We describe the implementation and performance of the
(Particle-Particle Particle-Tree) scheme for simulating dense stellar systems.
In , the force experienced by a particle is split into short-range
and long-range contributions. Short-range forces are evaluated by direct
summation and integrated with the fourth order Hermite predictor-corrector
method with the block timesteps. For long-range forces, we use a combination of
the Barnes-Hut tree code and the leapfrog integrator. The tree part of our
simulation environment is accelerated using graphical processing units (GPU),
whereas the direct summation is carried out on the host CPU. Our code gives
excellent performance and accuracy for star cluster simulations with a large
number of particles even when the core size of the star cluster is small
Non-intrusive hierarchical coupling strategies for multi-scale simulations in gravitational dynamics
Hierarchical code coupling strategies make it possible to combine the results
of individual numerical solvers into a self-consistent symplectic solution. We
explore the possibility of allowing such a coupling strategy to be
non-intrusive. In that case, the underlying numerical implementation is not
affected by the coupling itself, but its functionality is carried over in the
interface. This method is efficient for solving the equations of motion for a
self-gravitating system over a wide range of scales. We adopt a dedicated
integrator for solving each particular part of the problem and combine the
results to a self-consistent solution. In particular, we explore the
possibilities of combining the evolution of one or more microscopic systems
that are embedded in a macroscopic system. The here presented generalizations
of Bridge include higher-order coupling strategies (from the classic 2nd order
up to 10th-order), but we also demonstrate how multiple bridges can be nested
and how additional processes can be introduced at the bridge time-step to
enrich the physics, for example by incorporating dissipative processes. Such
augmentation allows for including additional processes in a classic Newtonian
N-body integrator without alterations to the underlying code. These additional
processes include for example the Yarkovsky effect, dynamical friction or
relativistic dynamics. Some of these processes operate on all particles whereas
others apply only to a subset.
The presented method is non-intrusive in the sense that the underlying
methods remain operational without changes to the code (apart from adding the
get- and set-functions to enable the bridge operator). As a result, the
fundamental integrators continue to operate with their internal time step and
preserve their local optimizations and parallelism.
... abridged ...Comment: Accepted for publication in Communications in Nonlinear Science and
Numerical Simulation (CNSNS) The associated software is part of the AMUSE
framework and can be downloaded from http:www.amusecode.or