Short noteA graphical user interface for particle-in-cell finite element analysis of lithospheric deformation and mantle convection in two dimensions☆
Introduction
This paper describes a graphical user interface (GUI) that has been developed for two-dimensional (2-D) simulations of lithospheric deformation and mantle convection. It was originally developed for the ellipsis simulation software (Moresi et al., 2003), but could also be adapted to other codes with similar objectives. Ellipsis is an open-source particle-in-cell finite element modelling system used in the geophysics and mechanical engineering community for research and teaching. The system has, in the past, required a considerable amount of expertise, as setting up simulations required editing complex parameter files. This work can often be frustrating, especially for novice users and students, and is prone to error. To resolve these problems, a GUI and documentation for use with the programme ellipsis has been created that facilitates more user-friendly entry into setting up ellipsis simulations.
Ellipsis simulates large deformations of materials using a finite element method where the problem domain is represented using an Eulerian mesh, in which Lagrangian integration points are embedded. Ellipsis is used primarily for simulations in which continuum solids display behaviour similar to that of fluids. Moresi et al. (2003)describe ellipsis in detail, especially the implementation of visco-elasticity, and provide details of several applications. Ellipsis has been applied to a number of problems including 2-D (Boschetti et al., 2003; Wijns et al., 2003; Dyksterhuis et al., 2007) and three-dimensional (O’Neill et al., 2006) lithospheric extension, mantle convection modelling with a visco-elastic/brittle lithosphere (Moresi et al., 2002), folding in finely layered visco-elastic rock structures (Muhlhaus et al., 2002), and the investigation of continental geotherms, heat flow and the survival of cratonic lithosphere through geological time (Lenardic, 1998; Lenardic et al., 2000, Lenardic et al., 2003; O’Neill et al., 2003).
Section snippets
A user friendly GUI for 2-D geodynamic modelling
Simulations using ellipsis must be set up by creating a text file, called an ellipsis input file. These files contains a long list of parameters, in the format parameter name=parameter value. These parameter settings control all aspects of the simulations, ranging from the types and locations of different materials in the simulation, the rheological properties of those materials, parameters controlling how much information ellipsis should provide about the simulation as it executes as well as
Scaling of model parameters
Perhaps the most difficult aspect of setting up an ellipsis simulation concerns scaling of the parameters. Some of the parameters used by ellipsis can have values with very great or very tiny magnitudes, and once calculations are performed on those parameters by ellipsis, the magnitudes of the resulting values can become even more extreme, which can result in the number becoming too big or too small to be represented accurately. This can lead to a loss of precision in the results of the
Code availability
The source code for the GUI as well as ellipsis have been released under the gnu public licence, and are available for download at www.earthbyte.org. Ellipsis can currently be compiled and run under any Unix-based operating system and also Windows operating systems (using Cygwin) while the GUI will run on any platform for which Java 1.4.2 or higher is available.
Acknowledgements
We would like to thank the Australian Research Council and ExxonMobil for supporting this work. We thank Mike Dowman and James Clark for their help with the code. The development of this GUI was inspired by a prototype GUI written by Craig O’Neill.
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Code available from server at http://www.iamg.org/CGEditor/index.htm or www.earthbyte.org.