Frequently Asked Questions

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. All mesh generation and simulation runs execute on cloud GPUs. You just need a modern web browser (Chrome, Firefox, Edge, or Safari).

What types of simulations can I run?#

Currently, Gradient Dynamics supports:

  • Steady-state RANS — The most common type of industrial CFD simulation

  • LES and DES — For transient, high-fidelity analysis (Pro tier and above)

The platform handles incompressible flow simulations for external aerodynamics, internal flows, thermal analysis, and rotating machinery.

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 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

My simulation diverged. What went wrong?#

The most common causes:

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

  2. Too aggressive relaxation factors (reduce by 30%)

  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.

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