Frequently Asked Questions

General

What is Gradient Dynamics Studio?

Gradient Dynamics Studio is a browser-based CFD (Computational Fluid Dynamics) platform. It allows you to upload CAD geometry, generate meshes, run flow simulations, and visualize results — all from your web browser with no software installation required.

Do I need to install anything?

No. Gradient Dynamics runs entirely in the browser. Mesh generation and simulation runs execute in the cloud. You just need a modern web browser (Chrome, Firefox, Edge, or Safari).

What types of simulations can I run?

Gradient Dynamics supports a comprehensive range of simulation types:

  • Steady-state RANS — The most common type of industrial CFD simulation (k-ω SST, k-ε, Spalart-Allmaras, RSM)

  • URANS — Time-accurate unsteady RANS for periodic or transient flows

  • LES — Large Eddy Simulation for high-fidelity turbulence resolution (Pro tier and above)

  • DES / DDES / IDDES — Hybrid RANS-LES methods for massively separated flows (Pro tier and above)

The platform handles compressible flow, incompressible flow, thermal analysis, rotating machinery, and coupled multiphysics workflows.

Is my data secure?

Your geometry files, meshes, and simulation results are stored securely in the cloud. Each user’s data is isolated and accessible only through your authenticated account.

Geometry

What file formats can I upload?

  • STEP (.step, .stp) — Recommended

  • IGES (.iges, .igs)

  • STL (.stl)

  • OBJ (.obj)

My geometry has issues. What should I do?

Run the geometry analysis in the Geometry tab. The most common fixes:

  1. Vertex welding — For STL/OBJ with small gaps between triangles

  2. Hole filling — For surfaces with missing patches

  3. CAD healing — For STEP/IGES with tolerance issues

The AI Assistant can also diagnose and recommend repairs.

How large can my geometry file be?

File upload limits depend on your subscription tier. For very large assemblies, consider simplifying the geometry by removing small features that don’t significantly affect the flow.

Meshing

How do I choose the right cell size?

Start with the geometry’s characteristic length divided by 50–100. For example:

  • 4.5 m car → Start with 0.05–0.1 m cell size

  • 50 mm pipe → Start with 0.5–1.0 mm cell size

Then refine until your results don’t change significantly between meshes (mesh independence).

What mesh types are available?

Studio supports unstructured and structured meshing. Unstructured meshing is the recommended starting point for most Studio workflows, especially production CFD, boundary-layer workflows, interoperability, and imported meshes. Structured meshing is available for automated, repeatable workflows where a structured approach fits the case.

What is y+ and why does it matter?

y+ is a dimensionless distance that describes the first cell height relative to the boundary layer thickness. It must match your turbulence model’s requirements:

  • y+ ≈ 30: Standard for wall-function RANS (k-ω SST, k-ε)

  • y+ ≈ 1: Required for wall-resolved simulations

The mesh settings tab includes a y+ calculator to help determine the correct first layer height.

Do I need boundary layers?

Yes, for almost all CFD simulations. Boundary layers resolve the velocity gradient at walls, which directly affects:

  • Drag prediction

  • Heat transfer rates

  • Separation behavior

  • Wall shear stress

Without boundary layers, results near walls will be inaccurate.

What geometry formats can I upload?

STEP (.step, .stp), IGES (.iges, .igs), STL, and OBJ. STEP is recommended as it preserves face topology and named faces, enabling automatic surface detection and per-face mesh controls.

Simulation

Which turbulence model should I use?

k-ω SST is the best default for most applications. Use k-ε for simple pipe flows, Spalart-Allmaras for quick estimates, and RSM for strongly swirling flows. See Turbulence Models for a detailed comparison.

How do I know if my simulation has converged?

  1. All residuals should be decreasing and reach at least 1e-4

  2. Integrated quantities (drag, lift, pressure drop) should be stable

  3. The residual plot should show a clear downward trend, not oscillations

Which solver should I choose?

For most applications, start with Automatic solver selection. Choose a specific solver family when your physics, validation target, or workflow requires it.

My simulation diverged. What went wrong?

The most common causes:

  1. Poor mesh quality (check skewness and non-orthogonality)

  2. Too aggressive startup or stability settings

  3. Incorrect boundary conditions (check all surfaces)

  4. Wrong geometry scale (verify dimensions are in meters)

See Troubleshooting for detailed guidance.

How many iterations do I need?

Typical ranges:

  • Simple geometries: 300–500 iterations

  • Moderate complexity: 500–1000 iterations

  • Complex geometries: 1000–2000 iterations

Start with 500–1000 and extend if residuals haven’t converged.

Credits and Billing

How are credits consumed?

Operation

Rate

Mesh generation

0.2 credits per GPU-minute

CFD simulation

1.0 credits per GPU-minute

Credit cost depends on mesh size and simulation duration.

Can I estimate the cost before running?

Yes. When you click Run Simulation or Generate Mesh, a cost estimate is shown before you confirm.

What happens if I run out of credits?

Jobs will not be submitted until credits are available. Credits reset monthly and overage billing options are available on higher tiers.

AI Assistant

What can the AI Assistant do?

The assistant can analyze geometry, recommend mesh settings, configure simulations, set boundary conditions, and interpret results. It works through natural language conversation.

Does the assistant automatically change my settings?

No. The assistant always asks for your explicit confirmation before making any changes to your project. You can review every action before it’s applied.

Can the assistant access my other projects?

No. The assistant only has context about the current project you’re working in.