Status¶

This page compares what femforge implements today with what its pipeline interfaces and its first solver backend, Elmer, offer. A row shows Implemented when the public config reaches it and the user guide documents it, Partial when a module or interface exists that the config cannot reach or the docs do not cover, and Not started when femforge has no model for it.

Pipeline interfaces¶

Each stage runs behind an interface, and one backend fills each interface today. Concepts walks through the pipeline that connects them.

Stage	Today	Interface	What a new implementation needs
Geometry	A tagged STEP file from any CAD, or a Build123dGeometry subclass	GeometryArea	A `build_step(path)` that writes a STEP whose body names carry the tags.
Mesh backend	GmshMesher in process, WorkerMesher in a child process	MeshBackend	A `mesh(job, out_dir)` that turns a `MeshJob` into Elmer mesh files and a `MeshReport`.
Solver backend	Elmer, through the typed solver stack in `femforge.elmer.config` and the sif writer	None yet	Conditions and materials emit Elmer keywords directly, so a second solver needs a solver-neutral interface first; see Solver objects.
Solver execution	NativeElmer for serial solves, DockerElmer for serial and MPI solves	ExecutionBackend	The `grid_convert`, `grid_partition` and `solve` methods and the `partitioned` flag of `src/femforge/elmer/runtime/backend.py`.
Optimization	GridSearch, `find_max_current`, and the `convergence_ladder` and `richardson` mesh-convergence helpers in `femforge.run`	Parameterization, Objective, DriverLike	A search that evaluates configs from a `Parameterization` through a `DriverLike` and records them in a Study.
Workbench	The trame workbench in `packages/femforge-workbench`	The `femforge.workbenches` entry point group	A function that returns a `Split`, declared as a WorkbenchSpec; see Workbench.

Frames¶

Elmer names eight coordinate systems. femforge maps two of them to a frame; see Frames.

Elmer coordinate system	femforge	Status
Cartesian 3D	Solid
Axi Symmetric	Axisymmetric
Cartesian 1D
Cartesian 2D
Polar 2D
Polar 3D
Cylindric
Cylindric Symmetric

CoordinateSystem in femforge.elmer.config already names Cylindric, Cylindric Symmetric and Polar as keyword values, but no frame maps a model onto them. A new frame needs a model in src/femforge/common/frame.py, a geometry conversion in src/femforge/geometry/frame.py and a case in Physics.in_frame.

Physics modules¶

The rows follow the chapters of the Elmer Models Manual. The femforge column names the Physics preset or the module that wires the Elmer module. A Not started module can still run through GenericSolver, which writes a hand-built solver block whose keywords femforge does not check. Conditions and physics documents each preset.

Heat and thermal¶

Elmer module	Solves	femforge
`HeatSolve`, `HeatSolveVec`	Heat conduction, with optional convection, radiation and temperature-dependent properties.	`Physics.THERMAL`, `Physics.JOULE_HEATING`
`PhaseChangeSolve` (transient)	The moving front between a liquid and a solid phase over time.
`PhaseChangeSolve` (steady state)	The steady position of a liquid-solid phase boundary.

Electromagnetics¶

Elmer module	Solves	femforge
`StatCurrentSolve`	The potential and current density in a conductor, and the Joule losses they produce.	`Physics.CURRENT_CONDUCTION`, `Physics.JOULE_HEATING`
`MagnetoDynamics`	The 3D magnetic field in A-V form on edge elements, static, time-harmonic or transient.	`Physics.MAGNETOSTATICS`, `Physics.COIL_MAGNETOSTATICS`; static only
`MagnetoDynamics2D`	The magnetic field of planar or axisymmetric problems from one component of the vector potential.	`Physics.MAGNETOSTATICS_2D`; axisymmetric static only
`CoilSolver`	A consistent current distribution through a coil, as a source for the magnetic solvers.	`Physics.COIL_MAGNETOSTATICS`
`StatElecSolve`	The electrostatic potential and field in dielectrics and conductors.	`Physics.ELECTROSTATICS`
`CircuitsAndDynamics`	Circuit equations coupled to a magnetoquasistatic model.
`VectorHelmholtz`	Time-harmonic electromagnetic waves at high frequency.
`EMWaveSolver`	Time-domain electromagnetic waves on edge elements.
`MagneticSolve`	The magnetic induction equation in a conducting fluid.
`StatElecBoundary`	Electrostatics between nearly parallel surfaces, reduced to one dimension.
`PoissonBoltzmannSolve`	The electric potential with free charges that follow a Boltzmann distribution.
`FourierLoss`	Electromagnetic losses from an on-the-fly Fourier series, in the Steinmetz style.
`ElectricForce`	The electrostatic force on a surface from a solved potential.
`StatMagSolve`	Axisymmetric magnetoquasistatics; Elmer marks it obsolete.

Physics.ELECTROSTATICS has a preset and documentation. FixedPotential feeds it only when its physics field is set to ELECTROSTATICS, and no guide page, example or test exercises that path.

Structural mechanics¶

Elmer module	Solves	femforge
`StressSolve`	Small displacements and stresses of a linear elastic solid.	`Physics.LINEAR_ELASTICITY`
`ElasticSolve`	Large deformations of an elastic solid.
`ShellSolver`	Deformations of thin curved shells.
`Smitc`	Bending of linear elastic plates.
`BeamSolver3D`	Forces and moments in elastic beams.
`SpringAssembly`	Point springs and masses added to a structural model.
`RigidBodyReduction`	A displacement problem reduced by treating some blocks as rigid.

Physics.LINEAR_ELASTICITY is a scaffold: no condition targets it, and the material model has no Poisson ratio.

Fluids¶

Elmer module	Solves	femforge	Status
`FlowSolve`	Incompressible or compressible viscous flow with the Navier-Stokes equations.
`AdvectionDiffusion`	Transport of a species or scalar by convection and diffusion.
`AdvectionReaction`	Transport of a passive scalar by a flow, with a reaction rate.
`ReynoldsSolver`	Pressure in a thin fluid film.
`Electrokinetics`	Flow of an electrolyte in small channels driven by electric surface charges.
`ParStokes`	Steady incompressible flow with block preconditioning for large systems.
`Stokes`	Incompressible flow in the rotational form of the Navier-Stokes equations.
`LevelSet`	The position of a free surface tracked with a level-set function.
`FreeSurfaceSolver`	A kinematic free surface, with limiters.
`FreeSurfaceReduced`	A free surface found from a constant flux condition.
`StructureFlowLine` (free surface)	A steady free surface in drawing and pulling processes, found along streamlines.
`ArtificialCompressibility`	A stabilizing compressibility term for loosely coupled fluid-structure interaction.
`FluidicForce`	The pressure and viscous force a flow exerts on a surface.
`RichardsSolver`	Flow through variably saturated porous media.
`ArteryOutlet`	An outlet boundary condition for blood flow in elastic arteries.

Acoustics and waves¶

Elmer module	Solves	femforge	Status
`HelmholtzSolve`	Time-harmonic acoustic pressure with the Helmholtz equation.
`Acoustics`	Linearized Navier-Stokes acoustics with viscous and thermal losses, in the frequency domain.
`WaveSolver`	A generalized scalar wave equation in the time domain.
`CompressibleNS`	Large-amplitude, nonlinear waves in air.
`HelmholtzBEM`	The Helmholtz equation with the boundary element method.

Particles and other¶

Elmer module	Solves	femforge	Status
`ParticleDynamics`	Trajectories of particles under forces and fields.
`ParticleAdvector`	Diffusion-free advection of fields by tracking particles backward in time.
`StructureFlowLine` (moving mesh)	Ordinary differential equations along an extruded mesh that moves with a draw velocity.
`ModelMixedPoisson`	The Poisson equation with the flux as a second unknown.
`PoissonBEM`	The Laplace equation with the boundary element method.
`BatterySolver`	Charge and species transport in a lithium-ion cell.
`DFTSolver`	Electronic structure with density functional theory; experimental in Elmer.

Utilities¶

Elmer module	Solves	femforge
`SaveScalars`	Reductions and integrals of fields, written as scalar values to a file.	`src/femforge/elmer/config/output/save_scalars.py`
`ResultOutputSolve`	Field output in VTU and other formats.	`src/femforge/elmer/config/output/result_output.py`
`MeshSolve`	Mesh deformation that follows moving boundaries.
`NonphysicalMeshSolve`	Mesh deformation where the mesh velocity does not matter.
`RigidMeshMapper`	Rigid rotation and translation of mesh bodies.
`StructuredMeshMapper`	A structured mesh fitted between given top and bottom surfaces.
`ElementStats`	Quality statistics of the mesh elements.
`StreamSolver`	Streamlines of a flow field.
`FluxSolver`	The flux of a Poisson-type field, such as heat flux.
`VorticitySolver`	The curl of a vector field.
`DivergenceSolver`	The divergence of a vector field.
`ScalarPotentialSolver`	The scalar potential whose gradient matches a given flux.
`FilterTimeSeries`	Averages and Fourier filters over time-series results.
`DataToFieldSolver`	A smooth field fitted to scattered data.
`ProjectToPlane`	A 3D field projected onto a plane.
`StructureProjectToPlane`	A field on a structured mesh projected onto its base surface.
`FindOptimum`	New design parameters from a cost function, inside one Elmer run.
`SaveLine`	Field values along lines through the mesh, written to a file.
`SaveMaterials`, `SaveBoundaryValues`	Material and boundary parameters stored as fields.
`SaveGridData`	Field values on a uniform Cartesian grid.
`Isosurface`	Isosurfaces or isolines extracted to reduce output.
`Elmer2OpenFoamIO`, `OpenFOAM2ElmerIO`	Field exchange with OpenFOAM through files.
`Probes`	Integrals of expressions over bodies.
`GmshOutputReader`	Fields read from a gmsh result file.
`ReloadData`	Earlier results loaded back during a run.
`ReloadInput`	The solver input reloaded while a run is in progress.
`GridDataReader`	NetCDF grid data interpolated onto the mesh.
Linear constraints (`SolverUtils`)	Linear constraints on a solve, enforced with Lagrange multipliers.
`XdmfWriter`	Parallel results written as Xdmf and HDF5.

femforge runs its sweeps and optimizations outside Elmer, so it uses none of the Elmer optimization utilities.

Solver capabilities¶

The rows follow the chapters of the ElmerSolver Manual that describe a capability a user switches on. The chapters on fundamentals, the input file format, compilation and programming, and the appendices on file formats and element definitions are background and have no row.

Elmer capability	Solves	femforge
Linear system methods	Direct, Krylov and multilevel solvers with their preconditioners.	LinearSystem fields on each solver
Nonlinear system options	Picard and Newton iteration, relaxation and convergence criteria.	NonlinearSystem fields on each solver
Parallel runs	Mesh partitioning and MPI solves.	DockerElmer with `mpi_processes`; see Elmer: Native and Docker
Restart	A run that starts from saved solutions.	`SimulationSettings.output_file` writes a restart file; nothing reads one back
Time integration	Transient solves with BDF, Newmark and other schemes.	`SimulationType.TRANSIENT` and `TimesteppingMethod`; every preset is steady state
Dirichlet conditions and limiters	Fixed values on boundaries, and soft limits on a solution.	Fixed values through `FixedTemperature` and `FixedPotential`; no limiters
Generic solver utilities	Solver activation, variable naming, exported variables and passive elements.	`exec_solver` and `variable` fields on SolverBase
Eigenvalue problems	Modes and eigenfrequencies of a system.
Shared boundary conditions	Periodic, mortar and conforming conditions between boundaries.
Linear constraints	Extra linear equations that couple degrees of freedom.
Constraint modes	The response to unit loads on chosen boundaries, as in a lumped model.
Nodal loads	Point loads, and the reaction loads of a solved system.
Block-matrix coupling	Tightly coupled multiphysics solved as one block system.
Meshing utilities	Coordinate transformation, mesh multiplication, extrusion and discontinuous interfaces inside Elmer.
Adaptive solution	Mesh refinement driven by an error estimate.
Higher-order elements	p-elements of higher polynomial order.

Conditions and materials¶

Every condition and material below is implemented. Conditions and physics and Materials document them.

Condition	Feeds	Target
Magnetization	`MAGNETOSTATICS`, `MAGNETOSTATICS_2D`, `COIL_MAGNETOSTATICS`	body
ForceComponent	`MAGNETOSTATICS`, `MAGNETOSTATICS_2D`, `COIL_MAGNETOSTATICS`	body
CurrentDensity	`MAGNETOSTATICS_2D`	body
CoilDrive	`COIL_MAGNETOSTATICS`	body
CoilTerminal	`COIL_MAGNETOSTATICS`	outer shell
FixedTemperature	`THERMAL`, `JOULE_HEATING`	boundary
HeatFlux	`THERMAL`, `JOULE_HEATING`	boundary
Convection	`THERMAL`, `JOULE_HEATING`	outer shell
HeatSource	`THERMAL`, `JOULE_HEATING`	body
FixedPotential	`CURRENT_CONDUCTION`, `JOULE_HEATING`	boundary
JouleHeat	`JOULE_HEATING`	body

Material	Tag	Notable properties
Air	`Air`	μr = 1, near-zero conductivity
Copper	`Copper`	Temperature-dependent conductivity
N52, N42	`N52`, `N42`	Temperature-dependent remanence and coercivity
FR4	`FR4`	εr = 4.5, glass transition temperature
Steel_1080	`Steel1080`	Nonlinear B-H curve, or a linear μr
Steel_316	`Steel316`	μr = 1.008, effectively non-magnetic

Picking a task¶

A row marked or is a candidate task. Contributing sets up a development checkout, and Solver objects shows how a solver model, a preset and a condition slot into the sif writer. Open or claim a task on the GitHub issues page.