[CIG-ALL] New PyLith release - version 1.5.0
baagaard at usgs.gov
Fri Jun 11 13:01:38 PDT 2010
I am pleased to announce the release of PyLith 1.5.0, a finite-element
code designed to solve dynamic elastic problems and quasi-static
viscoelastic problems in tectonic deformation.
This release adds several new features to PyLith, including (1) fault
friction with a few widely-used fault constitutive models, (2) an
optimized solver for explicit time-stepping with a lumped Jacobian
matrix, (3) a total Langrangian formulation for rigid-body motion and
small strains, (4) use of scientific notation in VTK output files with
user-specified precision, and (5) use of nodeset names in CUBIT Exodus
files. We encourage all users of previous PyLith releases to switch to
this latest release.
We strongly recommend all users of previous PyLith releases to switch
to this latest release. In addition to adding features this release
also fixes a number of bugs (see top-level README file). Also see the
README file for changes required to switch to the v1.5.x release
series from previous versions.
You can download the source code and binaries from
Detailed installation instructions are in the User Manual with example
installation procedures for a few platforms in the bundled doc/install
* Fault constitutive models
Added fault friction interface conditions with static
friction, linear slip-weakening friction, and rate- and
state-friction with the ageing law. The implementation can be used
in static, quasi-static, and dynamic problems.
* Drucker-Prager elastoplastic bulk rheology
Added a Drucker-Prager elastoplastic bulk rheology. This is a
perfect plasticity implementation (no hardening). This is a
nonlinear constitutive model, so the nonlinear solver is required
when this rheology is used. Refer to the 'Material Models' section
of the manual.
* Plane strain Maxwell viscoelastic bulk rheology
Linear Maxwell viscoelastic rheology for plane strain problems.
* Finite-deformation formulation
Added a finite-deformation (rigid body motion and small strains)
implementation of elasticity with stress calculated using the
Second Piola-Kirchhoff stress tensor and strains calculated using
the Green-Lagrange strain tensor.
* Lumped Jacobian for explicit-time stepping
Added the option to lump cell Jacobian matrices to form a diagonal
system Jacobian matrix for explicit time stepping. This decouples
all degrees of freedom and permits use of a fast, trivial, direct
* Optimized elasticity objects
Added optimized elasticity objects for the most popular cell types
and basis functions (linear polynomials). For tri3 and tet4 cells
with one quadrature point, the optimized implementations do not
use mapped cells to reduce the number of operations.
* Scientific notation for ASCII VTK files
Data values in ASCII data files are written in scientific notation
with user-specified precision.
* Nodeset names in CUBIT Exodus files
Use of nodeset names in CUBIT Exodus files for boundary conditions
and faults. Users can specify to use nodeset names (default
behavior) or ids.
* Velocity and slip rate as output fields
Velocity (domain and subdomain) and slip rate (fault) fields are
can be requested as output fields. The fields are computed using
the time-stepping algorithm and alleviates the need to compute
them via post-processing.
* Dimensionless values in spatial databases no longer need
artificial dimensions. Values without dimensions are understood by
the parser as dimensionless quantities.
* Bug fixes
- Updating state variables did not retrieve physical properties
for cell. Last physical properties retrieved were used. Physical
properties are now retrieved when updating state variables.
- Fixed incorrect dimensioning of physical properties and state
variables for the power-law rheology in output.
- Fixed memory bug for a fault in a 1-D mesh when constructing the
More information about the CIG-ALL