SSP Project Summary
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Visualisation of 2D and 3D Discrete Element Models using OpenGL

Student

Dimitrios Mitsotakis, University of Crete

Supervisor

David Henty, EPCC

A Discrete Element Model (DEM) simulates the behaviour of a collection of particles, typically interacting via a short-range force. The simulation works at the level of individual particles and in real cases many millions are typically required to get accurate results. Examples include simulating snooker balls (a 2D DEM with simple contact forces), the way ball bearings pack as they are emptied into a box (a 3D DEM with complicated contact forces including friction) or the fracturing behaviour of a crystal at the atomic level (a 3D DEM with complicated short-range forces extending at least as far as an atom's nearest neighbours). EPCC has been involved in many projects involving parallel DEMs, and visualisation is always very important, not least because animations of DEMs can be extremely visually attractive as well as scientifically informative. The supervisor of this project is currently working with a DEM from the Department of Physics, and would very much like animations of the results.

Each of the previous projects was visualised with a tailor-made solution using either AVS or OpenGL. Although AVS is very flexible, it is rather heavyweight for the straightforward task of rendering simple particles, and it is not easy to do real-time animation with many particles. OpenGL is a simple, portable and efficient standard for 3D graphics (and actually underlies AVS), available on Unix and NT, which is ideal for animation. The aim of this project is to develop a simple OpenGL visualiser for DEMs that reads a file containg the particle positions as a function of time and animates them. There are many possibilities for adding interesting functionality, for example: colour-coding the particles based on static or dynamic properties; leaving streamlines to track a particle's motion; taking cuts through the data to reveal inner structure; presenting the visualisation from the point of view of one of the particles; adding visualisation of bonds; etc. etc. An important by-product will be to develop more experience of OpenGL within EPCC, and to make use of our visualisation hardware.

The final report for this project is available here.
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