Since 2.9 release

Assembly function

Improved Pickling support

Discrete functions can now be directly pickled and will be reconstructed with the grid on load. The required JIT modules will also be generated on load if they do not exist on the system. For this to work one needs to use the dune.common.pickle module as discussed in the Section on pickling.

Paraview Reader

A paraview reader is added to the dune.fem package which can directly work with the pickled files. UFL transformations can be applied after loading the discrete functions in paraview. For paraview to find the reader a environment variable needs to be set. The correct command can be found running python -m dune.fem reader or the correct env variable can be set by running

export PV_PLUGIN_PATH=`python -m dune.fem readerpath`

See https://gitlab.dune-project.org/dune-fem/dune-fem/-/merge_requests/581.

Sampler along Boundary

In addition to a lineSample and pointSample the dune.fem.utility module now also provides a boundarySample function

boundarySample(gridFunction, boundaryId=None, boundaryDomain=None, order=-1)

See the help text of dune.fem.utility.boundarySample for details.

Improved Dirichlet Boundary Indexing in UFL Forms

To restrict a domain integral to a part of the boundary given by a boundary id one can now use ufl.ds(id) or multiply the integral with dune.ufl.BoundaryId(id) (see the section on Mixing different types of boundary conditions.

Note: we have also unified the default boundary ids when using a dune.grid.cartesianDomain to always be the same as when using dune.grid.structuredGrid. This was not the case with some grid implementations.