V4.3 beta is finally ready for download (beta - because the manual still needs to be updated)
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.
V4.3 may probably be the final version of TRANSIENT.
TRANSIENT V4.3 is available as a source code. Also supplied is the source code for the four demonstration PDMs, makefiles to generate binaries from the demonstration PDMs for Linux, UNIX, MS Windows and others, and a set of sample input and output files. The code is expected to work without changes with any ANSI C compiler. A fully updated manual will be supplied as soon as possible (Latex, HTML, PDF, Postscript - the menu on the left will be updated).
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 very simplified 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.
Download the latest TRANSIENT distribution package from here:
transientV4.3-beta.tgz.
It is a gziped tar archive of size 438,004 bytes; md5sum: a92f8723c2ab03914f4ced03dfb345a5.
(Right click, choose 'Save Link Target As...')
For those who would like to first try TRANSIENT in MS Windows without going through compilation, download this "standard set of demo executables" (see makefile) compiled in Cygwin: transient.V4.3-beta-demos-win.zip (a zip archive of size 1,627,011 bytes). It includes cygwin1.dll, so there is no need to install Cygwin on your computer. Just unpack this zip file, and you can run the demos in an ordinary Commnand Prompt window.
On a UNIX-like machine, copy the downloaded file transientV4.3-beta.tgz for example into the parent directory of an empty directory into which you want to install TRANSIENT, cd to this directory, and type:
gunzip < ../transientV4.3-beta.tgz | tar xf -
On MS Windows, one can use 7zip/WinRAR/WinZip to extract the contents of transientV4.3-beta.tgz into an empty directory.To find how to compile and use TRANSIENT, read the documentation embedded in the extracted archive, or the online manual (on the left).
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.