elmer-sim

name	elmer-sim
description	Use when driving Elmer FEM (open-source multi-physics finite-element suite from CSC-IT) via `.sif` solver-input files — heat/elasticity/electromagnetics/fluid multiphysics, through sim runtime one-shot execution on Linux.

elmer-sim

You are connected to Elmer FEM via sim-cli.

Elmer is an open-source multi-physics FEM code from CSC (Finland). A case is defined by:

• .sif — Solver Input File (block-structured text)
• mesh directory — referenced via Mesh DB "." "meshname" in Header block; contains mesh.header, mesh.nodes, mesh.elements, mesh.boundary

Execution: ElmerSolver case.sif. Output: case.vtu (ParaView, name set by Post File in Simulation block).

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base/ — always relevant

Path	What's there
base/reference/sif_blocks.md	.sif block structure (Header, Simulation, Body, Material, Solver, BC).
base/reference/mesh_workflow.md	ElmerGrid usage; native mesh format; Gmsh → Elmer conversion.
base/reference/solver_catalog.md	Built-in solvers: HeatSolve, StressSolver, MagnetoDynamics, etc.
base/snippets/01_heat_square.sif	Verified heat-equation E2E snippet.
base/known_issues.md	Build flags, mesh conversion quirks.

solver/26.1/ — Elmer FEM 26.1 specifics

• solver/26.1/notes.md — source build info, dependencies.

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Hard constraints

1. Mesh directory must exist before solving. Reference via Mesh DB "dir" "meshname" means files live in <dir>/<meshname>/.
2. Block ordering matters: Header → Simulation → Constants → Body → Material → Body Force → Initial → Equation → Solver → BC.
3. Active Solvers list in an Equation block ties solvers to bodies. Bodies without an Equation reference are passive.
4. Acceptance != exit code. Check the .vtu output or stdout residual history for physical validity.
5. End closes every block — missing End causes cryptic parse errors far from the mistake.

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Required protocol

After sim check elmer: gather Category A inputs (physics, geometry source for mesh, BCs, material properties, acceptance criteria). Generate mesh (ElmerGrid from .grd, or Gmsh→Elmer). Write .sif. Lint with sim lint. Run with sim run --solver elmer. Parse .vtu or stdout for validation.