PyLith v3.0.0 released

PyLith
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PyLith v3.0.0 now available

I am pleased to announce the release of PyLith 3.0.0, a finite-element code designed to solve dynamic elastic problems and quasistatic viscoelastic problems in tectonic deformation.

This major release is the result of more than 5 years of work to overhaul the code in support of a wide range of new features.

You can download the source code and binaries from
https://geodynamics.org/resources/pylith

Documentation
https://pylith.readthedocs.org/en/v3.0.0

Migrating from version 2.X TO 3.0.0

Version 3.0.0 includes major changes to the underlying finite-element formulation and implementation in order to support a more flexible specification of the governing equations and higher order basis functions. These changes affect how simulations are defined. Parameter files for previous versions will need to be updated; the changes are too complex for a simple translation table. Some features present in v2.2.2, such as spontaneous rupture and finite strain, have not yet been implemented in the new formulation.

Release Notes

  • Multiphysics
    • Elasticity for linear isotropic materials and linear Maxwell, generalized Maxwell, and power law viscoelastic models
    • Incompressible elasticity for linear isotropic materials
    • Prescribed slip for quasistatic and dynamic simulations
  • Higher order basis functions
    Allow user to select order of basis functions independent of the mesh (which defines the geometry). This permits higher resolution for a given mesh.
  • Switch to using PETSc time-stepping (TS) algorithms
    Replace simple Python-based time-stepping implementations with PETSc time-stepping algorithms that provide support for higher order discretization in time and real adaptive time stepping.
  • Static Green’s functions with user-specified discretization of fault slip impulses
  • Import finite-element meshes from Cubit (Exodus II), Gmsh, and LaGriT
  • Modular approach for initial conditions
  • Output of subfields with user-defined basis order
  • Simulation metadata with command line utility for searching metadata
  • Convert to Python 3
  • Convert LaTeX documentation to Sphinx + MyST
  • Testing with the Method of Manufactured Solutions
  • Automatically assign label value for fault cohesive cells (id setting is obsolete).
  • Use description for descriptive labels and label and label_value for tagging entities. PyLith’s use oflabel and label_value now corresponds to PETSc labels and label values.

Deprecated features

We plan to discontinue support for reading LaGriT mesh files in version 3.2. Gmsh provides an open-source alternative with a graphical user interface.

Known issues

  • Running in parallel has a few minor bugs due to communication mismatches and over-aggressive error checking. We will be fixing these in the next week.
  • We will be updating the 3D subduction zone example (examples/subduction-3d) to v3.0.0 in the next week, including providing the input mesh file; in the meantime do not attempt to run this example.
  • We have included Gmsh in the binary packages. For Linux there are additional libraries that must be installed for Gmsh to run; these are associated with the graphical user interface and included in most default installations.

Contributors

  • Brad Aagaard
  • Matthew Knepley
  • Charles Williams
  • Robert Walker
  • Chris Mills
  • Shengduo Liu
  • Thea Ragon
  • Alex Berne
  • Jed Brown
  • Rey Koki
  • Kali Allison
  • Lorraine Hwang
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