Particula:Particula Numerica

From Physica_Numerica

Contents 1 Overall 1.1 First 1.2 What is Particula 1.3 What Particula can do 1.3.1 Initial Condition 1.3.2 File I/O 1.3.3 Simulation Control 1.3.4 Visualization 1.3.5 Movie (a series of images) Creation 1.4 Characteristics 1.4.1 Multi-Thread 1.4.2 SIMD vectorized 1.4.3 Two additional Algorithms for effective computation 1.5 The others 1.6 Acknowledgement 1.7 Have fun! 2 Download 3 Installation 4 Screen Shot 5 Change Log

Overall

First

Particula is still in beta quality as of July 2008 but upgrade to 0.31 gaining several functions. Several bugs in 0.1 are fixed but still beta quality, please consider it when you use it. Here is a description about 0.2. If you are interested in the latest version click here. As the very first step, you might be intersted in the Installation instruction. If you already installed the software, you might want to see the First Step.

What is Particula

Thank you for your interest in my software "Particula Numerica" in shortly "Particula" which is an Gravitational N-Body Simulator. The software give you REAL-TIME three dimensional images for gravitationally interacting bodies, which are thought to be stars. REAL-TIME isn't meant real stellar time but you can see the MOTION of stars. The time indicated in the software is normalized time. You have the actual time by muliplying by a factor:

,

where M, R and G is a mass unit, length unit and gravitational constant, respectively.

What Particula can do

Initial Condition

Particula can simulate the gravitational interaction of many bodies with certain initial conditions. You can set a simple homo-temperature spherical distribution model as an initial condition. The temperature and the number of the particles are able to be set. You can also use NEMO ASCII files (stoa) as an initial data.

File I/O

Particula can read/save NEMO file format. If you don't familiar with NEMO please check it at: http://bima.astro.umd.edu/nemo/

Simulation Control

You can set the total simulation time. You can start/stop when you like.

Visualization

Particula provide you both two and three dimensional view. It shows you the overall 3D view of the particles. In 2D view you can see a trajectory of a certain particle and the temporal variation of potential energies (Kinetic/red and Potential/blue). To update the 2D view you should click mouse with Ctrl key or the right mouse button. To change the line of sight in 3D view, just drag to rotate and shift-drag to zoom in/out.

Movie (a series of images) Creation

From 0.2, Particula can save images of 3D visual to a series of images. The image is exactly same with the 3DView window. You can set the interval of saving image with preference panel (Preference menu). The interval indicates the iteration number of time-step to save image.

Characteristics

Multi-Thread

Particula is multi-thread-ed so you would get the benefit of multi-core processors.

SIMD vectorized

Particula is vectorized for SIMD architectures. So far only Macintosh (PowerPC and Intel) version has the benefit.

Two additional Algorithms for effective computation

You can select one of three algorithms for computation in simulation control (Sim Ctrl) menu. The three algorithms are Direct, Oct-Tree and AD-Tree. When the number of particles are less than 1000, Direct is the most effective and less than 10000 Oct-Tree is effective. More than 10000 AD-Tree would be most effective. Direct method is a method just add the whole Newtonian force between any two particles. Oct-Tree method is a Octal-Tree based method as usual adopted. AD-Tree stands for Alternate digital tree and is used instead of Oct-Tree.

The others

Particula binaries (Mac/IntelMac/Windows) are available free of charge. You can redistribute the software to anyone you want. You are expected to contact me when you would copy/distribute for commercial use.

Acknowledgement

The author of the software is grateful to the Open Source Communities for the useful software, which are wxWidgets, wxmathplot and Pthread, GLUT for win32, they are specific for MS Windows.

Have fun!

The author of the software is ABE Hiroshi. You can reach me at:

habe36 at gmail.com

ABE Hiroshi, from Tokorozawa, JAPAN. 15th May 2007.

Download

Particula Numerica version 0.2 binaries are avalable from this site.
You can get MacOS X version (Universal Binary)
Also you can get Windwos Version

NEMO stoa ASCII example input file is avalable at here
The data file is generated by NEMO Toolkit. To generate the same data by NEMO toolkit, you should enter as:
% mkexpdisk out=disk2k nbody=2048
% stoa in=disk2k out=disk2k.ascii

You can get previous MacOS X version (Universal Binary)
Also you can get previous Windwos Version

Installation

Here is an installation instruction of Particula Numerica.

Screen Shot

Here is a screen shot of MacOS X version.

Change Log

Here is the change log of the software.