DevelopmentPlan 2019 04

PyLith Development Plan, April 2019

Version 3.0 (June 2019)

• Multiphysics [30%]

  • Implement modular approach for specifying governing equations and computing residuals and Jacobians.
  • Incompressible elasticity via a pressure field [20%]

• Higher order basis functions [100%]

  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. [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.

• Modular approach for initial conditions

• Testing via Method of Manufactured Solutions

Version 3.1

• Improve fault formulation for spontaneous rupture [10%]

  Removes inner solve associated with updating Lagrange multipliers. This will significantly accelerate the nonlinear solve.

• Add additional multiphysics implementations and rheologies

  • Poroelasticity [5%]

Version 3.2

• Convert to Python 3
• 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
• Radial basis functions for spatial databases

Version 4.0

• Earthquake cycle modeling

  Same mesh for dynamic and quasi-static parts (dynamic → quasi-static, quasi-static → dynamic, complete cycle)

• Create strain hardening/softening 2-D and 3-D Drucker-Prager elastoplastic models.

• Moment tensor point sources [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

  • 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.

  • Data assimilation

    Use flexibility of multiphysics implementation to support inclusion of data assimilation

• Minor features

  • Begin implementation of data assimilation capabilities via adjoint equation.

  • 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.