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Geometry Management

The first step in any CFD simulation is importing your geometry. The Navier AI Platform makes this process simple while ensuring your geometry is simulation-ready.

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Supported File Formats

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Primary Format

  • STL Files: The preferred format for robust, predictable imports
    • Binary STL (recommended for smaller file sizes)
    • ASCII STL (human-readable but larger files)
    • Maximum recommended size: 100MB for optimal performance

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File Preparation Best Practices

Resolution Settings:
  • Fine/High resolution for curved surfaces
  • Coarse acceptable for flat surfaces
  • Target: 10-50k triangles for simple geometries
Units:
  • Export in meters (platform default)
  • Consistent units throughout geometry
  • Verify scale after import
Requirements:
  • Watertight mesh (no holes or gaps)
  • Proper normal orientation (outward-facing)
  • Clean intersections between components
  • Reasonable aspect ratios
Tools for Checking:
  • CAD software validation tools
  • Mesh repair utilities (Netfabb, Meshlab)
  • Platform automatic validation

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Upload Process

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Step-by-Step Upload

  1. Access Geometry Section
    • Click “Geometry” in the simulation tree
    • Select “Upload Geometry” button
  2. File Selection
    • Browse and select your STL file
    • Drag-and-drop supported
    • Multiple files can be uploaded for assemblies
  3. Automatic Processing
    • File validation and error checking
    • Automatic scaling detection
    • Geometry bounds calculation
    • Surface area and volume computation

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Visual Verification

3D Viewer

Interactive 3D visualization with:
  • Rotation, zoom, and pan controls
  • Surface shading and wireframe modes
  • Measurement tools
  • Multiple viewing angles

Geometry Statistics

Automatic calculation of:
  • Bounding box dimensions
  • Surface area
  • Volume (if watertight)
  • Characteristic length

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Coordinate System

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Platform Standards

  • X-axis: Streamwise direction (flow direction)
  • Y-axis: Lateral/spanwise direction
  • Z-axis: Vertical direction (up)
  • Origin: Can be adjusted in domain setup

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Orientation Guidelines

Best Practice: Orient your geometry so the primary flow direction aligns with the positive X-axis. This ensures consistent domain setup and boundary condition application.
Common Orientations:
  • Aircraft/Drones: Nose pointing +X, wings along Y
  • Vehicles: Front pointing +X, width along Y
  • Buildings: Primary wind direction as +X

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Geometry Validation

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Automatic Checks

The platform performs several validation checks:
  • Watertight Test: Ensures closed surfaces
  • Normal Consistency: Verifies outward-facing normals
  • Intersection Detection: Identifies overlapping surfaces
  • Scale Verification: Confirms reasonable dimensions

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Error Resolution

Symptoms:
  • Volume calculation fails
  • Meshing errors
  • Inconsistent boundary detection
Solutions:
  • Use CAD repair tools
  • Fill holes in original model
  • Check for coincident surfaces
Symptoms:
  • Interior surfaces visible
  • Incorrect flow behavior
  • Mesh generation issues
Solutions:
  • Fix normal orientation in CAD
  • Use mesh repair software
  • Re-export with proper settings
Symptoms:
  • Extremely large or small domains
  • Unrealistic simulation parameters
  • Performance problems
Solutions:
  • Verify export units
  • Check characteristic dimensions
  • Use geometry scaling tools

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Multi-Component Assemblies

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Assembly Management

  • Upload multiple STL files for complex assemblies
  • Each component becomes a separate patch
  • Automatic component detection and naming
  • Individual material property assignment

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Component Organization

Assembly Example:
├── Main_Body.stl
├── Wing_Left.stl  
├── Wing_Right.stl
├── Propeller_1.stl
└── Landing_Gear.stl

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Patch Assignment

Each component automatically becomes a boundary patch:
  • Individual boundary condition assignment
  • Material property control
  • Visualization grouping
  • Result analysis by component

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Geometry Preprocessing

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Automatic Enhancements

The platform automatically:
  • Repairs minor mesh defects
  • Optimizes triangle quality
  • Removes duplicate vertices
  • Improves surface smoothness

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Manual Adjustments

Available tools include:
  • Scaling: Resize geometry if needed
  • Translation: Adjust position relative to origin
  • Rotation: Orient geometry for optimal flow alignment

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Advanced Features

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Feature Recognition

  • Sharp Edges: Automatic detection for mesh refinement
  • Thin Sections: Identification of challenging geometry
  • High Curvature: Areas requiring mesh density
  • Surface Roughness: Boundary layer considerations

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Simulation Readiness

Mesh Quality

Geometry analysis for optimal mesh generation

Flow Features

Identification of critical aerodynamic features

Domain Planning

Automatic domain size recommendations

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Common Workflows

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Simple Single Body

  1. Upload single STL file
  2. Verify orientation and scale
  3. Proceed to domain setup

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Multi-Component Assembly

  1. Upload all component files
  2. Verify relative positioning
  3. Check component boundaries
  4. Assign individual properties

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Parametric Studies

  1. Upload baseline geometry
  2. Prepare multiple variants
  3. Set up batch processing
  4. Compare results systematically

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Troubleshooting

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Upload Issues

  • File Size: Reduce geometry complexity or compress
  • Format: Ensure proper STL format
  • Corruption: Re-export from original CAD

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Display Problems

  • Missing Surfaces: Check file completeness
  • Incorrect Scale: Verify export units
  • Poor Quality: Increase export resolution

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Performance Optimization

  • Large Files: Use mesh decimation tools
  • Complex Geometry: Simplify non-critical features
  • Memory Usage: Split large assemblies
Next Step: Once your geometry is uploaded and validated, proceed to Domain Configuration to set up your computational domain.