dgd -- D Gas Dynamics

This repository hosts our collection of tools, written mainly in the D programming language, to simulate compressible flows. Our focus is open source code that is designed to be a simple access point for teaching students about CFD codes.

Contents

• Eilmer -- A compressible flow solver
  • Features
  • Documentation
  • Build Requirements
  • Running the program
• License
• Contributors
• Chief Gardeners

Eilmer -- A compressible flow solver

Presently, the principal code in this collection is the Eilmer simulation code for 2D and 3D gas dynamic flows that may involve chemical reactions. It is a research/education code and, with its built-in grid generation capabilities, is suitable for the exploration of flows where the bounding geometry is not too complex.

Features:

• Eulerian/Lagrangian description of the flow (finite-volume, 2D axisymmetric or 3D).
• Transient, time-accurate, optionally implicit updates for steady flow.
• Shock capturing plus shock fitting boundary.
• Multiple block, structured and unstructured grids.
• Parallel computation in a shared-memory context.
• High-temperature nonequilibrium thermochemistry.
• GPU acceleration of the finite-rate chemistry.
• Dense-gas thermodynamic models and rotating frames of reference for turbomachine modelling.
• Turbulence models.
• Conjugate heat transfer to solid surfaces and heat flow within solid objects.
• MHD simulation for a single-fluid plasma (a work in progress).
• Import of GridPro structured grids and SU2 unstructured grids for complex flow geometries.

We have structured the code as a programmable program, with a user-supplied input script (written in Lua) providing the configuration for any particular simulation exercise. Our target audience is the advanced student of gas dynamics, possibly an undergraduate student of engineering but, more likely, a postgraduate student or academic colleague wanting to simulate gas flows as part of their study.

Documentation

The documentation for users of the code is in a set of PDF reports at the Eilmer web site http://cfcfd.mechmining.uq.edu.au/eilmer/ Presently there are user guides for the main simulation code, the geometry package and the gas model package. More documents will appear as they are completed.

For those brave souls prepared to dive into the use and extension of the code, there are examples provided as well as the source code itself. For the short term, with the code in a period of rapid development, we expect that users of the code will be mainly our students and academic colleagues who can talk to us directly.

Build Requirements

Once you have cloned this repository, all that is required is a Linux environment with a fairly recent D compiler for building the main code, a C compiler for building the Lua interpreter, and a Fortran-2003 compiler for building some of the thermochemical models.

You may use the reference DMD compiler or the GDC or LDMD2 compilers. We have been developing with the recent DMD32 and DMD64 compilers, from version 2.073. For the C and Fortran compilers, we use gcc and gfortran.

Beyond having a standard Linux system with recent compilers, the build of the Lua interpreter requires the development packages for libreadline and libncurses. The MPI version of the code requires packages mpi-default-bin and mpi-default-dev (on Debian-flavoured Linux distributions).

Going into the dgd/src/eilmer directory you will find a single makefile that allows the build to proceed with the command make install. The executable program and supporting files will be installed into the directory $HOME/dgdinst/ by default.

Running the program

For running the program, environment variables may be set for the bash shell with:

export DGD_REPO=${HOME}/dgd
export DGD=${HOME}/dgdinst
export PATH=${PATH}:${DGD}/bin
export DGD_LUA_PATH=${DGD}/lib/?.lua
export DGD_LUA_CPATH=${DGD}/lib/?.so

Setting DGD_REPO may be handy if you have cloned your copy of the repository to somewhere other than $HOME/dgd/.

The actual running of a simulation is done in stages.

1. Prepare the grids and initial flow configuration by interpreting your Lua input script.
2. Run the main simulation program, starting from the prepared initial flow state and allowing the flow field to develop in time, writing the resulting flow field states at particular times.
3. Postprocess the simulation data to extract particular data of interest.

Of course, this description is too superficial to actually expect that you will be able to run a simulation with no further instruction. If you are keen, it's now time to look at the PDF documents mentioned above and then look at specific examples provided in the dgd/examples/eilmer/ directory.

License

For the source code, we use the GNU General Public License 3. Please see the file gpl.txt. For the documentation, we use the Creative Commons Attribution-ShareAlike 4.0 International License.

Contributors

This code is the product of many people. Please see the file contributors.txt for some details of who has written what part of the code. The commit history is place to go to see further details.

Chief Gardeners

Peter Jacobs and Rowan Gollan, 2015-08-31 -- 2018-01-16