Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/oliverzh2000/parallel-barnes-hut
A parallelized and efficient C++ implementation of the Barnes-Hut algorithm for simulating an N-body system.
https://github.com/oliverzh2000/parallel-barnes-hut
astrophysics barnes-hut-algorithm parallel-computing
Last synced: 28 days ago
JSON representation
A parallelized and efficient C++ implementation of the Barnes-Hut algorithm for simulating an N-body system.
- Host: GitHub
- URL: https://github.com/oliverzh2000/parallel-barnes-hut
- Owner: oliverzh2000
- License: gpl-3.0
- Created: 2019-12-21T00:41:26.000Z (about 5 years ago)
- Default Branch: master
- Last Pushed: 2021-01-01T00:08:10.000Z (about 4 years ago)
- Last Synced: 2024-11-14T07:12:06.673Z (3 months ago)
- Topics: astrophysics, barnes-hut-algorithm, parallel-computing
- Language: C++
- Homepage:
- Size: 13.7 MB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Parallel 3D Barnes-Hut N-Body Simulation
#### Version 2.0.0
A parallelized and high-performance C++ implementation of the [Barnes-Hut algorithm](https://en.wikipedia.org/wiki/Barnes-Hut_simulation) for simulating an N-body system and visualizing it.
CUDA GPU acceleration, interactive simulation viewer, lossy simulation data compression, and optimized support for other compilers (non-GCC) coming soon. See [Roadmap](#roadmap)
# Gallery
The above is a fast-forwarded and reduced resolution render from an older project.
Full-size 3D demo coming soon. Simulation in progress on Google Compute Engine.
# Getting Started
1. Checkout the repo from github, and build the project with `cmake`
```bash
$ git clone https://github.com/oliverzh2000/parallel-barnes-hut.git
$ cd parallel-barnes-hut
$ cmake ./ DCMAKE_BUILD_TYPE=RelWithDebinfo
$ make
$ ./nbody --help
```
See [Command Line Options](#command-line-options) for detailed usage information.
2. Initialize the simulation with between `~10^7` and `~10^8` stars with random positions and velocities and then leave the system running for a few days, weeks, or even months. See [Recommended Parameter Values](#recommended-parameter-values) for some general tips.
- **Important!** Make sure you have enough disk space to store the simulation results. _(Coming soon)_ You can use the `--estimate` command line option to get an estimate of the disk space needed to store the simulation results at your specified level of detail as well as an estimate of the time needed to run the simulation.
3. _(Coming soon)_ Sign up for an email notification when your simulation completes.
4. _(Coming soon)_ Come back when finished and view your spectacular results on the simulation viewer.
# Command Line Options
Run the simulation driver (the `nbody` executable) with `--help` for more information.
Use `--sim-directory` to give the simulation driver a path to a directory. This directory must contain an `init.txt` that is used to specify all the parameters of the simulation.
### Format of `init.txt`
```
integratorType: 'IntegratorLeapfrog' | 'IntegratorEuler'
timestep: positive-decimal
forceCalcType: 'ForceCalcAllPairs' | 'ForceCalcBarnesHut' | 'ForceCalcBarnesHutParallel'
gravConst: positive-decimal
softening: positive-decimal
theta: positive-decimal-value *1.
starsInitMode: 'readStarsInline' | 'readStarsFromLatestBinaryFrame' | 'readStarsFromLatestShortFrame' |createSpiralGalaxy'
n: number-of-stars
pos-x pos-y pos-z vel-x vel-y vel-z mass
...
... n rows total, one per star *2.
n: number-of-stars
centerPos:
x: decimal
y: decimal
z: decimal
centerVel:
x: decimal
y: decimal
z: decimal
radialStdDev: positive-decimal
avgMass: positive-decimal
avgMassStdDev: positive-decimal
seed: integer *3.
```
**Notes:**
1. Use this field only with a Barnes-Hut force calculator type.
2. Use this section only with `readStarsInline` star initialization mode.
3. Use this section only with `createSpiralGalaxy` star initialization mode.
All units are specified in SI: meters, seconds, kilograms, radian, etc.
#### Example usages of `init.txt`
```
integratorType: IntegratorLeapfrog
timestep: 0.01
forceCalcType: ForceCalcBarnesHutParallel
gravConst: 1.0
softening: 0.01
theta: 0.5
starsInitMode: readStarsFromLatestBinaryFrame
```
```
integratorType: IntegratorLeapfrog
timestep: 0.01
forceCalcType: ForceCalcBarnesHutParallel
gravConst: 1.0
softening: 0.01
theta: 0.5
starsInitMode: createSpiralGalaxy
n: 100000
centerPos:
x: 0
y: 0
z: 0
centerVel:
x: 0
y: 0
z: 0
radialStdDev: 100
avgMass: 1
avgMassStdDev: 0.1
seed: 0
```
```
integratorType: IntegratorLeapfrog
timestep: 0.01
forceCalcType: ForceCalcBarnesHutParallel
gravConst: 1.0
softening: 0.01
theta: 0.5
starsInitMode: readStarsInline
n: 5
0 8 0 0 0 0 1
5 7 0 0 0 0 1
5 5 0 0 0 0 1
7 5 0 0 0 0 1
8 0 0 0 0 0 1
```
# Recommended Parameter Values
| Parameter | Recommended value | Reason |
| :------------- |:-------------| :-----|
| `integratorType` | `integratorLeapfrog` | 2nd-order compared to Euler and is time-reversible |
| `forceCalcType` | `ForceCalcBarnesHutParallel` | Better performance than non-parallel counterpart and the all-pairs quadratic-time algorithm is simply infeasible for large datasets |
| `theta` (if applicable) | `0.5` or `1` | `0.5` gives very good accuracy. `1` gives acceptable accuracy at better performance |
# Roadmap
# License