V4.2 coming very soon! It will not last too much longer, I promise.
TRANSIENT is a C program for solving arbitrary systems of generally nonlinear, parabolic partial differential equations in two variables (space and time), in particular, reaction-diffusion equations. An efficient original adaptive time-stepping algorithm is applied. User has to supply a problem definition module (PDM) for each system of equations to be solved. Demonstration PDMs for four different problems are supplied with the package.
V3.0 represents a major improvement of TRANSIENT: a transient run is now much less prone to failure, see History. V3.11 is a further upgrade of V3.0.
TRANSIENT is available as a source code. TRANSIENT V3.11 is supplied with a 42 page long manual (Latex, HTML, Postscript - see the menu on the left), source code for the four demonstration PDMs, makefiles to generate binaries from the demonstration PDMs for Linux, UNIX, MS Windows and VMS, and a set of sample input and output files. The code is expected to work without changes with any ANSI C compiler.
One of the demonstration PDMs deals with the simulation of uniform corrosion of a copper surface, and the diffusion of the corrosion products into an adjacent porous layer (clay) followed by another porous medium (rock). This model uses a nonequidistant spatial grid in order to treat adequately the important region near the corroding surface. TRANSIENT's adaptive time-stepping algorithm enabled to carry the integration easily up to 1 billion years. Long-term modeling of such systems with uneven evolution in time in relatively short CPU time with reasonable precision seems to be the strength of TRANSIENT. The second demonstration PDM deals with gas production in a closed space. The third one is concerned with an idealized model of stochastic surface growth, and the fourth one with the Brusselator model of mathematical biology.
For the solution of the discretized nonlinear algebraic equations for each time step, TRANSIENT uses an optimized Newton-Raphson algorithm.
You would be able to download the TRANSIENT distribution package
from here, when finally available: transientV4.2.tbz.
(As a bziped tar archive). To download it, right click on this link, and choose 'Save Link As ...'.
Executables for MS Windows for the very old demonstration examples: transV3.0.demos.zip. If you do not have Cygwin installed on your computer, you will need a DLL file called cygwin1.dll to run them. Unpack it in the same directory where you unpacked transV3.0.demos.zip, or in your path. Run the demos from the command line of an MS-DOS prompt window.
On a UNIX-like machine, copy the downloaded file transientV4.2.tbz for example into the parent directory of an empty directory into which you want to install TRANSIENT, cd to this directory, and type:
gunzip < ../transientV4.2.tbz | tar xf -On MS Windows, one can use WinZip to extract the contents of transientV4.2.tbz into an empty directory.
To learn how to compile and use TRANSIENT, read the online manual (on the left), download its Postscript version, or produce it from the LaTeX source transien.tex that you will find in the `doc' subdirectory of the unpacked archive.
In the root directory of the unpacked package double-click on index.html. From there your can explore TRANSIENT in your Web browser. Preferably start with the 'readme' files 00readme.txt and demo/0readme.txt.
Makefiles for compilation are supplied.
A PDM can be written for you for simple cases according to your complete mathematical specification (set of partial differential equations, boundary and initial conditions). Inquire by e-mail.