PyLith Development Plans, May 2017

Priorities for PyLith software development, such as new features and enhancements. This a draft for community comment (May 19, 2017).

This plan attempts to balance meeting short-term objectives of delivering high priority, new features and meeting long-term objectives of extending the code to solve a broader range of scientific problems.

Version 3.0 (2017)

1. Multiphysics 30%
   • Implement modular approach for specifying governing equations and computing residuals and Jacobians.
   • Incompressible elasticity via a pressure field 20%
2. Higher order basis functions 50%
   • Allow user to select order of basis functions independent of the mesh (which defines the geometry). This permits higher resolution for a given mesh.
3. Switch to using PETSc time-stepping (TS) algorithms. 75%
   • 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.
4. Update user manual
   • Convert from LyX to LaTeX for ease of maintenance and editing. 100%
   • Reorganize for multiphysics implementation. 10%
   • Reorganize examples. 5%
     • Focus on demonstrating the range of physics and features beginning with simple cases and building towards more complex cases.
     • Include ParaView Python scripts for plotting results.
     • Consider moving examples to Jupyter notebooks; export to PDF files for “print” documentation.

Version 3.1 (early 2018)

1. Improve fault formulation for spontaneous rupture 10%
   • Removes inner solve associated with updating Lagrange multipliers. This will significantly accelerate the nonlinear solve.
2. Allow full specification of the initial conditions (solution and state variables) 0%
3. Add additional multiphysics implementations and rheologies
   • Poroelasticity 5%
4. Convert to Python 3 and Pyre 1.0.

Version 3.X (TBD)

1. Add additional multiphysics implementations and rheologies
   • Drucker-Prager bulk rheology with relaxation to yield surface
   • Elasticity + heat flow

Reorganize output for time-dependent Green’s functions and adjoints

Multilevel nonlinear solve

Use threading to accelerate integrations on multi-core machines.

Version 4.0 (TBD)

1. Earthquake cycle modeling
   • Same mesh for dynamic and quasi-static parts (dynamic -> quasi-static, quasi-static -> dynamic, complete cycle)
2. Create strain hardening/softening 2-D and 3-D Drucker-Prager elastoplastic models.
3. Moment tensor point sources via equivalent body forces 5%
   • Moment tensor point sources provide a mesh independent deformation source that is better suited for Green’s function calculations than slip on a fault surface via cohesive cells.

Features for Future Releases

Major features

1. Earthquake Cycle Modeling
   • Different meshes for dynamic and quasi-static parts
     • Requires interpolation of fields between different meshes/discretizations and may require extrapolation of solutions when quasi-static problems span a larger domain than the dynamic problems.
2. Data assimilation
   • Use flexibility of multiphysics implementation to support inclusion of data assimilation

Minor features

1. Begin implementation of data assimilation capabilities via adjoint equation.
2. Combined prescribed slip / spontaneous rupture fault condition
   • Use fault constitutive model to control slip on fault except during episodes of prescribed slip. Need some way to describe when to turn on/off prescribed slip.

difficulty rating system

easy

intermediate

difficult

expert

based on the ski trail rating system

Created on 23 Jan 2021, Last modified on 23 Jan 2021