[CIG-ALL] PyLith 0.8.2 beta release

[Charles Williams]

Greetings,

I am pleased to announce the beta version 0.8.2 release of PyLith, a  
finite element code designed to solve quasi-static viscoelastic  
problems in lithospheric dynamics.  The latest release offers the use  
of traction boundary conditions, load histories for split nodes, a  
number of new
material models, including power-law Maxwell and generalized Maxwell  
(3 Maxwell models in parallel), the use of .cfg files for setting  
simulation parameters, much simpler top-level code structure, and  
several bug fixes.

You can download the source code from

   http://geodynamics.org/cig/software/packages/short/pylith

Installation instructions are in the bundled README and INSTALL files.

Release Notes:

1.  The code now makes use of time histories for split node fault  
displacements, allowing users to slip different faults (or sections  
of a fault) according to a given history.  The format of split node  
input files has not changed, since time histories were still present  
in the input files (they were just ignored).

2.  Traction boundary conditions were broken in the previous version  
of PyLith, and they are now functioning for both tetrahedral  
(triangular faces) and hexahedral (quadrilateral faces) elements.

3.  There are now 6 different material models in PyLith:
IsotropicLinearElastic:  Standard elastic model that was available  
previously
IsotropicLinearMaxwellViscoelastic:  New formulation for the Maxwell  
viscoelastic model
IsotropicLinearGenMaxwellViscoelastic:  New material model consisting  
of a spring in parallel with 3 linear Maxwell models
IsotropicPowerLawMaxwellViscoelastic:  New power-law Maxwell model  
using the Effective Stress Function approach
IsotropicLinearMaxwellViscoelasticESF:  Previous formulation of the  
linear Maxwell model using the Effective Stress Function approach
IsotropicPowerLawMaxwellViscoelasticZT:  New formulation for the  
power-law Maxwell model using a formulation based on that of  
Zienkiewicz & Taylor

4.  The ability to use .cfg files means that this is now the  
preferred method for setting parameters in PyLith, rather than the  
command line or using .pml files. These files have a very simple  
format, and setting up simulations should now be much simpler.

5.  The top-level code structure has been much simplified.  The  
primary benefit of this to users (in addition to more efficient  
code), is that there are no longer separate pylith3d.scanner  
options.  Instead, there are now just pylith3d options.  Also, PETSc  
options may now be set as 'petsc.xxx=yyy' in a .cfg file.


While this release should be useful to many researchers, we are  
presently focusing our efforts on PyLith 1.0, which will be the first  
version of the code to include both quasi-static and dynamic  
capabilities.  We will make an announcement on this list when the  
initial version of PyLith 1.0 is released.



Charles A. Williams
Dept. of Earth & Environmental Sciences
Science Center, 2C01B
Rensselaer Polytechnic Institute
Troy, NY  12180
Phone:    (518) 276-3369
FAX:        (518) 276-2012
e-mail:    willic3 at rpi.edu


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