Frequently Asked Questions

No. FlowEngine is pay-per-use with no account required. You pay via Stripe, upload your case, and receive a status page URL. Bookmark that URL to check progress and download results.

We support standard OpenFOAM dictionary format compatible with OpenFOAM v10 and later. Your case should use standard OpenFOAM dictionary syntax (not YAML or JSON format).

See our supported solvers list for the full list of solver applications we accept.

UCF solvers are our proprietary solver variants that include adaptive relaxation, divergence containment, and early-stop detection. They improve convergence robustness compared to stock OpenFOAM solvers.

By default, converge runs use UCF solvers when available for your case type. Your case files are executed as-is — we don't change your physics, boundary conditions, or mesh. The solver variant used is recorded in your evidence pack.

Standard tier: $75 for validation, plus $175 for an optional converge run ($250 total).

Professional tier: $250 for validation, plus $1,250 for a converge run ($1,500 total). Higher cell limits and longer wall time.

See full pricing details on our home page.

No. You can use FlowEngine for validation only ($75). After validation, you'll see the option to upgrade to a converge run if your case passes. The upgrade is entirely optional.

The validation fee ($75) is non-refundable once your case is uploaded. The converge run fee ($175) is non-refundable once execution begins.

If a failure is caused by a platform error (our infrastructure, not your case), contact support@ucfflowengine.com for review.

Full details in our Terms of Service.

All payments are processed through Stripe. We accept credit cards (Visa, Mastercard, Amex), debit cards, and other payment methods supported by Stripe in your region.

Upload a .zip file containing a standard OpenFOAM case directory with system/, constant/, and 0/ directories. See our directory structure guide for details.

You need either a pre-built mesh in constant/polyMesh/ or a system/blockMeshDict. If you include a blockMeshDict, we run blockMesh automatically during preflight to generate the mesh.

If neither is present, the case will be rejected.

You get 3 validation attempts per intake (Standard tier). If your first upload fails, review the validation evidence pack for the specific reason, fix the issue, and re-upload using the same intake link.

Common reasons: forbidden constructs (#codeStream, coded*), missing required files, or exceeding tier limits.

Upload links expire 24 hours after payment. Make sure to upload your case within that window. If the link expires before you upload, contact support@ucfflowengine.com.

500 MB for both Standard and Professional tiers. Remove old time directories and unnecessary output files before zipping to reduce size. Only include the 0/, constant/, and system/ directories.

Your primary download is a branded PDF report with color-coded pass/fail results, risk assessment, mesh analysis, and (if errors are found) step-by-step fix recommendations. Converge runs produce a PDF run report with execution summary and convergence details.

Raw evidence artifacts are also available: JSON manifests, stability reports, SHA256 checksums, solver logs, and (for converge runs) an HMAC-SHA256 seal for tamper-proof verification.

See our sample reports page for a detailed preview.

The seal is a cryptographic signature generated by the worker that executed your case. It covers every file in the run output using HMAC-SHA256. The gateway independently verifies the seal before marking your run as complete.

This provides tamper-proof evidence that your results were generated by FlowEngine and haven't been modified. Seals are included with converge runs only (not validation-only intakes).

Evidence packs and all artifacts are retained for 90 days from creation. Download your results within that window. After 90 days, data may be deleted without notice.

We recommend downloading your evidence pack as soon as it's available.

Your run completes as a "partial completion." You still receive the full evidence pack with all data generated up to that point, including solver logs and any intermediate results.

Standard tier: If your Standard run times out at 2 hours, you can upgrade to Professional for $1,075 ($1,250 Professional price minus a $175 credit from your Standard run). This re-runs your case with 48-hour wall time, 16 cores, and 32 GB RAM — no re-upload needed. This offer is available for 7 days after your run completes.

Professional tier: If your Professional run hits the 48-hour limit, contact support@ucfflowengine.com to discuss extended compute options.

Yes. Uploads go directly to encrypted cloud storage via presigned URLs. Each case runs in an isolated environment with no network access during execution. We don't share your data with third parties.

See our Privacy Policy for full details.

You do. Your case files remain your property. Evidence packs generated from your data are yours to use and distribute. We retain a processing license only for the duration needed to provide the service.

Yes. Contact support@ucfflowengine.com to request early deletion. We retain minimal metadata (run IDs, timestamps, billing records) for audit purposes.

This means your bundle failed structural checks (before physics validation). Common causes:

Missing job_spec.json — Every bundle needs a job_spec.json at the ZIP root. See requirements for the format.

Invalid ZIP — The file isn't a valid ZIP archive, or it's corrupted during upload.

Path traversal detected — Your ZIP contains paths with ../ sequences, which are blocked for security.

Zip bomb detected — Compression ratio is suspiciously high. Re-pack your case normally.

Your validation PDF includes specific error codes with fix recommendations. The most common:

MISSING_CONTROL_DICT — No system/controlDict found. Ensure your case directory structure is correct.

FORBIDDEN_CONSTRUCT — Your case uses #codeStream, coded* function objects, or embedded executables. Remove these and use standard OpenFOAM entries.

MESH_LIMIT_EXCEEDED — Your mesh exceeds the cell count limit for your tier (5M Standard, 50M Professional).

PARAM_OUT_OF_BOUNDS — A numerical parameter (deltaT, relaxation factor, etc.) is outside accepted bounds. Check the parameter bounds table.

MISSING_BOUNDARY — Required boundary condition files are missing from the 0/ directory.

Exit code 1 means the solver encountered a fatal error during execution. Common causes include divergence (residuals went to infinity), mesh quality issues, or incompatible boundary conditions.

Your evidence pack still contains all data generated before the failure, including solver logs. Check the logs for the specific error message.

If you believe this is a platform issue rather than a case issue, contact support@ucfflowengine.com with your Run ID.

Large meshes and transient simulations can take significant time. Standard tier allows up to 2 hours, Professional up to 48 hours. Check the turnaround estimates for typical times based on mesh size.

If your run is still showing "running" after the wall-time limit for your tier, it may be completing final artifact packaging. Wait 15 minutes. If it still hasn't updated, contact support.

Check the confirmation email sent after payment (from noreply@ucfflowengine.com) or your Stripe receipt. Both contain your intake/run ID which can be used to reconstruct the status URL.

If you can't find either, email support@ucfflowengine.com with the email address you used at checkout and we'll locate your intake.

Simulations run on dedicated AWS instances with NVMe storage for fast I/O. Standard tier gets up to 8 vCPUs and 16 GB RAM. Professional tier gets up to 16 vCPUs and 32 GB RAM.

Each run gets exclusive access to its compute resources — no shared-tenancy or noisy neighbors.

Validation: We run 60+ automated checks against your case before execution — catching mesh issues, dictionary errors, and stability risks that would otherwise waste compute time.

Solver robustness: UCF solvers include adaptive relaxation ratcheting and divergence containment. Cases that diverge with stock OpenFOAM often converge with UCF variants.

Evidence trail: Every run produces a tamper-proof evidence pack with cryptographic seals — useful for audits, regulatory submissions, or client deliverables.

No setup: No OpenFOAM installation, no cluster management, no debugging MPI errors. Upload a ZIP, get results.

You don't need to. FlowEngine handles domain decomposition and parallel execution automatically based on your mesh size and tier. If you include a system/decomposeParDict, it will be used; otherwise we generate one optimized for the allocated core count.

Standard OpenFOAM: simpleFoam, pimpleFoam, icoFoam, pisoFoam, interFoam, rhoSimpleFoam, rhoPimpleFoam, potentialFoam

UCF Enhanced: UCF_simpleFoam (incompressible steady-state), UCF-SimpleCompressibleFoam (compressible steady-state), UCF_rhoSimpleFoam, UCF_rhoPimpleFoam

When you submit a case, the solver is detected from your controlDict and automatically routed to the appropriate engine. UCF solver variants are used by default when available for your solver type.

Yes. Each intake is independent. You can submit and pay for multiple cases simultaneously — each gets its own queue position, worker, and evidence pack. There's no limit to concurrent submissions.