Simulation Validator

Goal

Provide a three-stage validation protocol: pre-flight checks, runtime monitoring, and post-flight validation for materials simulations.

Requirements

• Python 3.8+
• No external dependencies (uses Python standard library only)
• Works on Linux, macOS, and Windows

Inputs to Gather

Before running validation scripts, collect from the user:

Input	Description	Example
Config file	Simulation configuration (JSON/YAML)	simulation.json
Log file	Runtime output log	simulation.log
Metrics file	Post-run metrics (JSON)	results.json
Required params	Parameters that must exist	dt,dx,kappa
Valid ranges	Parameter bounds	dt:1e-6:1e-2

Decision Guidance

When to Run Each Stage

Is simulation about to start?
├── YES → Run Stage 1: preflight_checker.py
│         └── BLOCK status? → Fix issues, do NOT run simulation
│         └── WARN status? → Review warnings, document if accepted
│         └── PASS status? → Proceed to run simulation
│
Is simulation running?
├── YES → Run Stage 2: runtime_monitor.py (periodically)
│         └── Alerts? → Consider stopping, check parameters
│
Has simulation finished?
├── YES → Run Stage 3: result_validator.py
│         └── Failed checks? → Do NOT use results
│                            → Run failure_diagnoser.py
│         └── All passed? → Results are valid

Choosing Validation Thresholds

Metric	Conservative	Standard	Relaxed
Mass tolerance	1e-6	1e-3	1e-2
Residual growth	2x	10x	100x
dt reduction	10x	100x	1000x

Script Outputs (JSON Fields)

Script	Output Fields
scripts/preflight_checker.py	report.status, report.blockers, report.warnings
scripts/runtime_monitor.py	alerts, residual_stats, dt_stats
scripts/result_validator.py	checks, confidence_score, failed_checks
scripts/failure_diagnoser.py	probable_causes, recommended_fixes

Three-Stage Validation Protocol

Stage 1: Pre-flight (Before Simulation)

1. Run scripts/preflight_checker.py --config simulation.json
2. BLOCK status: Stop immediately, fix all blocker issues
3. WARN status: Review warnings, document accepted risks
4. PASS status: Proceed to simulation

python3 scripts/preflight_checker.py \
    --config simulation.json \
    --required dt,dx,kappa \
    --ranges "dt:1e-6:1e-2,dx:1e-4:1e-1" \
    --min-free-gb 1.0 \
    --json

Stage 2: Runtime (During Simulation)

1. Run scripts/runtime_monitor.py --log simulation.log periodically
2. Configure alert thresholds based on problem type
3. Stop simulation if critical alerts appear

python3 scripts/runtime_monitor.py \
    --log simulation.log \
    --residual-growth 10.0 \
    --dt-drop 100.0 \
    --json

Stage 3: Post-flight (After Simulation)

1. Run scripts/result_validator.py --metrics results.json
2. All checks PASS: Results are valid for analysis
3. Any check FAIL: Do NOT use results, diagnose failure

python3 scripts/result_validator.py \
    --metrics results.json \
    --bound-min 0.0 \
    --bound-max 1.0 \
    --mass-tol 1e-3 \
    --json

Failure Diagnosis

When validation fails:

python3 scripts/failure_diagnoser.py --log simulation.log --json

Conversational Workflow Example

User: My phase field simulation crashed after 1000 steps. Can you help me figure out why?

Agent workflow:

1. First, check the log for obvious errors:

   python3 scripts/failure_diagnoser.py --log simulation.log --json
   

2. If diagnosis suggests numerical blow-up, check runtime stats:

   python3 scripts/runtime_monitor.py --log simulation.log --json
   

3. Recommend fixes based on findings:
   • If residual grew rapidly → reduce time step
   • If dt collapsed → check stability conditions
   • If NaN detected → check initial conditions

Error Handling

Error	Cause	Resolution
Config not found	File path invalid	Verify config path exists
Non-numeric value	Parameter is not a number	Fix config file format
out of range	Parameter outside bounds	Adjust parameter or bounds
Output directory not writable	Permission issue	Check directory permissions
Insufficient disk space	Disk nearly full	Free up space or reduce output

Interpretation Guidance

Status Meanings

Status	Meaning	Action
PASS	All checks passed	Proceed with confidence
WARN	Non-critical issues found	Review and document
BLOCK	Critical issues found	Must fix before proceeding

Confidence Score Interpretation

Score	Meaning
1.0	All validation checks passed
0.75+	Most checks passed, minor issues
0.5-0.75	Significant issues, review carefully
< 0.5	Major problems, do not trust results

Common Failure Patterns

Pattern in Log	Likely Cause	Recommended Fix
NaN, Inf, overflow	Numerical instability	Reduce dt, increase damping
max iterations, did not converge	Solver failure	Tune preconditioner, tolerances
out of memory	Memory exhaustion	Reduce mesh, enable out-of-core
dt reduced	Adaptive stepping triggered	May be okay if controlled

Limitations

• Not a real-time monitor: Scripts analyze logs after-the-fact
• Regex-based: Log parsing depends on pattern matching; may miss unusual formats
• No automatic fixes: Scripts diagnose but don't modify simulations

References

• references/validation_protocol.md - Detailed checklist and criteria
• references/log_patterns.md - Common failure signatures and regex patterns

Version History

• v1.1.0 (2024-12-24): Enhanced documentation, decision guidance, Windows compatibility
• v1.0.0: Initial release with 4 validation scripts