N-body simulation using Barnes-Hut

A parallel implementation of the Barnes-Hut tree algorithm for performing N-body simulation.

Group members

1. Samyak Jain
2. Nihar Dwivedi

Instructions for running the code:

1. Run the following command to know the number of available threads on your test system-

    lscpu

The number of threads is (number of cores * the number of threads per core) given by this command. The number of threads given as command line argument for step 3 should be less than or equal to this value.

2. Run the following commands to compile the project-

    cd src
    make

3. Execute the compiled executable by runnning it with the given command line arguments -

    ./barneshut <thread count> <number of clusters> <number of bodies>
                <number of simulation steps> <theta for quadtree>
                <random seed for initialization> [output file]

4. The results of the simulation will be saved in the [output file] that's saved in the same location.

Documentation

The comeplete project report with the results and outputs can be found in the project report in the Documentation folder.

Result Observations

The best results are obtained by using 8 threads. When the number of threads exceed 8, the overhead of managing the extra threads exceeds any gains from using extra threads. The theta value can have a range between 0 and 1. For optimal results, we have used a theta value between 0.1 and 0.5.