Highlights • The multiphysics models that involve mechanics can now use the Two-Point Stress Approximation as an alternative to the Multi-Point Stress Approximation. To do so, include the mixin classes 'TpsaMomentumBalanceMixin' for mechanical problems and 'TpsaPoromechanicsMixin' for (thermo)-poromechanical problems. Be aware that TPSA is inconsistent on general grids and should be used with some caution. • The single phase model problem defined as Case 2 in the benchmark for flow discretizations has been added, see 'src/porepy/examples/flow_benchmark_3d_case_2.py'. This was contributed to @jhabriel. • A hybrid upstream weighting scheme for discretizing multiphase flow in the presence of gravity, partly following this paper. This functionality was contributed by @OmarDuran. Be aware that, due to computational bottlenecks in the parsing of Ad expressions, the assembly of the hybrid upstream weighting is currently quite slow. Improving this will be a priority in the coming months. API breaking changes • The method initialize_default_data is removed. The method initialize_data should be used instead. • In the Grid class, the method cell_diameters no longer accepts the parameters cell_nodes. • The following methods have been moved from the module fvutils.py: o diagonal_scaling_matrix is moved to matrix_operations.py o map_subgrid_to_grid is moved to partititon.py and renamed subgrid_to_grid_mapping. The module fvutils is now a pure helper module for finite volume discretizations and marked as private. • The parameters controlling the line search non-linear solver now uses lowercase keys. Minor fixes and enhancements • An overview of all top-level parameters that enter the multiphysics models is now available in src/porepy/examples/example_params.py. • Functions have been added to move cell centers to the cell circumcenters when this is inside the cell, see the module src/porepy/grids/grid_utils.py. This technique can be used to increase the accuracy of TPSA (and TPFA). • Computational speed related to parsing of Ad updating • In the Ad framework, SparseAdArray and DenseAdArray objects are now immutable. In addition, there has been several minor fixes and performance improvements. Contributors The following users have contributed code to this release: • @vlipovac • @jhabriel • @OmarDuran • @IvarStefansson • @Yuriyzabegaev • @pschultzendorff • @ingridkj • @wmboon • @mikeljordan • @mariusnevland • @zhangyh • @copilot • @keileg Full Changelog: https://github.com/pmgbergen/porepy/compare/v1.11...v1.12