# Boundary Layer Refinement

Boundary layer refinement generates prismatic layers near wall surfaces to accurately resolve viscous effects and boundary layer phenomena, which is crucial for capturing wall shear stresses, heat transfer, and flow separation.

# 📋 Available Options

Option Description Unit
First layer thickness Height of the initial prismatic layer length (e.g. m)
Assigned surfaces Target surfaces for boundary layer application -

# 🔍 Detailed Descriptions

# First Layer Thickness

Specifies the height of the initial prismatic layer adjacent to the wall.

  • Default: None (required)
  • Example: 1e-5 * u.m
  • Notes: Critical for achieving desired y+ values and resolving viscous effects

# Assigned surfaces

Identifies the wall surfaces where boundary layer refinement will be applied.

  • Default: None (required)
  • Example: [wing_surface, fuselage_surface]
  • Notes: Must reference valid wall surface entities in the geometry

💡 Tips
  • Set first layer thickness based on desired y+ value and flow conditions
  • Use growth rates between 1.1 and 1.3 for optimal resolution
  • Consider Reynolds number when determining layer thickness
  • Ensure sufficient layers for boundary layer development
  • Balance resolution requirements with computational cost

❓ Frequently Asked Questions

  • How do I determine appropriate first layer thickness?

    Calculate based on desired y+ value, Reynolds number, and flow conditions using appropriate scaling laws.

  • What happens if boundary layer refinements overlap?

    The finest (smallest) first layer thickness will be applied in overlapping regions.

🐍 Python Example Usage

 
from flow360 import BoundaryLayer, u

# Boundary layer refinement for wing
bl_ref = BoundaryLayer(
    name="wing_bl",
    faces=[wing_surface],
    first_layer_thickness=1e-5 * u.m,
)

# Boundary layer refinement for high Reynolds number flow
high_re_bl = BoundaryLayer(
    name="high_re_bl",
    faces=[high_re_surface],
    first_layer_thickness=1e-6 * u.m,  # Smaller for higher Reynolds number
)

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