openfoam-41-error-message-format

name	openfoam-41-error-message-format
description	Sub-skill of openfoam: 4.1 Error Message Format (+2).
version	1.0.0
category	engineering
type	reference
scripts_exempt	true

4.1 Error Message Format (+2)

4.1 Error Message Format

--> FOAM FATAL ERROR:
    <description>
    From function <Class>::<method>
    in file <source.C> at line <N>.
FOAM exiting

4.2 Common Failures and Fixes

1. Floating Point Exception (exit code 136)

Cause	Diagnosis	Fix
Courant number too high	Check Courant Number max: in log	Enable adjustTimeStep yes; maxCo 1; or reduce deltaT
Poor mesh quality	Run checkMesh -allTopology -allGeometry	Fix cells with non-orthogonality > 70, negative volumes
Zero/negative k or epsilon	Check 0/ initial values	Set k > 0 and epsilon > 0 everywhere
Bad turbulence initialization	Residuals blow up immediately	Start laminar, then switch to turbulent

2. GAMG Solver Divergence

Symptoms: p residuals stuck near 1.0, or oscillating without decreasing.

Cause	Fix
Mesh too coarse	Refine mesh at critical regions
Bad relaxation factors	Reduce: p from 0.3 to 0.2, U from 0.7 to 0.5
Non-orthogonal mesh	Increase nNonOrthogonalCorrectors to 1-3
GAMG agglomeration failure	Switch to solver PCG; preconditioner DIC; for p

3. Missing Field/File

FOAM FATAL IO ERROR: cannot find file ... /0/k

Fix: ensure all fields required by the turbulence model exist in 0/. See table in Section 1.6.

4. Boundary Condition Mismatch

FOAM FATAL ERROR: patch type 'xxx' not constraint type ... for patch yyy

Fix: patch types in 0/ files must match boundary types in constant/polyMesh/boundary. If mesh defines empty, all field files must use empty for that patch.

5. Courant Number Blowup (transient)

Courant Number mean: 0.5 max: 150.3

Solver	Acceptable maxCo
icoFoam (PISO)	< 1 (strict)
interFoam (VOF)	maxCo < 1, maxAlphaCo < 1
pimpleFoam (nOuterCorrectors > 1)	up to 5-10

6. Convergence Stall (simpleFoam)

Residuals plateau or oscillate without decreasing.

Action	How
Reduce relaxation	U: 0.5-0.7, p: 0.2-0.3
Enable consistent SIMPLE	consistent yes; in SIMPLE dict
Initialize with potentialFoam	potentialFoam -writephi before simpleFoam
Check BCs	Ensure mass balance (inlet flux = outlet flux)

7. Out of Memory (exit code 137)

Action	How
Reduce mesh	Coarsen or reduce refinement levels
Use parallel	decomposePar + mpirun -np N distributes memory
Use binary write	writeFormat binary; in controlDict
Increase swap	System-level: sudo fallocate -l 8G /swapfile

8. Parallel Decomposition Errors (exit code 255)

Symptom	Fix
numberOfSubdomains mismatch	Must match -np N in mpirun
Missing processor directories	Run decomposePar first
Inconsistent mesh across processors	Re-run decomposePar

9. snappyHexMesh Failures

Symptom	Fix
Empty mesh after castellated step	Check locationInMesh is inside domain, not inside geometry
Feature edge artifacts	Increase nFeatureSnapIter to 10-20
Layer addition failure	Reduce nSurfaceLayers, increase minThickness
STL not found	Check path in geometry {} block, use triSurfaceMesh type

10. Dimension Mismatch

FOAM FATAL ERROR: dimensions not compatible

Fix: check dimensions line in 0/ field files against the reference table (Section 1.8). Common mistake: using absolute pressure dimensions [1 -1 -2 0 0 0 0] instead of kinematic [0 2 -2 0 0 0 0] for incompressible solvers.

4.3 Mesh Quality Thresholds

Metric	OK	Warning	Fail
Non-orthogonality max	< 65	65-80	> 80
Skewness	< 4	4-10	> 10
Aspect ratio	< 100	100-1000	> 1000
Min volume	> 0	near 0	< 0 (inverted)
Min determinant	> 0.001	0.0001-0.001	< 0

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