Refinements

Refinements#

This document provides an overview of mesh refinement capabilities in Flow360. Refinements enable precise control over mesh resolution in specific regions of your geometry to better capture flow features or geometric details.

Available Refinement Types#

Refinement type

Description

Surface Edge Refinement

Controls mesh resolution near edges

Surface Refinement

Controls surface mesh cell size

Boundary Layer Refinement

Creates prismatic layers near walls

Passive Spacing

Controls mesh behavior without direct refinement

Uniform Refinement

Creates uniform mesh spacing in a region

Axisymmetric Refinement

Creates structured-like mesh with cylindrical bias

Geometry Refinement

Controls mesh resolution based on geometric features

General Guidelines#

Refinement Selection#

  1. Surface Features

    • Use Surface Edge Refinement for leading/trailing edges

    • Apply Surface Refinement for general surface resolution

    • Implement Boundary Layer Refinement for wall regions

    • Select geometry refinement to accurately capture small features

  2. Off-Body Features

    • Use Uniform Refinement for wakes and shocks

    • Apply Axisymmetric Refinement for rotating machinery

    • Consider Passive Spacing for interface regions

Best Practices#

  • Start with coarser refinements and gradually increase resolution where needed

  • Ensure smooth transitions between regions of different refinement levels

  • Consider geometric scale when setting refinement parameters

  • Balance resolution requirements with computational cost

  • Account for flow regime and Reynolds number effects

Common Applications#

  1. Aerodynamic Simulations

    • Surface Edge Refinement for leading edges

    • Boundary Layer Refinement for wall regions

    • Uniform Refinement for wake regions

  2. Rotating Machinery

    • Axisymmetric Refinement for rotor/propeller regions

    • Boundary Layer Refinement for blade surfaces

    • Uniform Refinement for tip vortex regions

  3. Complex Geometries

    • Surface Refinement for general resolution

    • Passive Spacing for interface regions

    • Uniform Refinement for critical flow features

💡 Tips

  • Review detailed documentation for each refinement type

  • Consider flow physics when selecting refinement types

  • Use appropriate units for all parameters

  • Ensure compatibility between different refinements

  • Monitor mesh quality metrics

❓ Frequently Asked Questions

  • How do I choose between different refinement types?

    Consider the geometric features and flow phenomena you need to resolve, then select the most appropriate refinement type(s).

  • What happens if refinements overlap?

    The finest (smallest) spacing will be used in overlapping regions.

  • How do I ensure mesh quality?

    Monitor aspect ratios, skewness, and other quality metrics while adjusting refinement parameters.

🐍 Python Example Usage

 
import flow360 as fl

# Example of combining multiple refinements
meshing=MeshingParams(
    refinements=[
        # Surface edge refinement for leading edge
        fl.SurfaceEdgeRefinement(
            name="leading_edge",
            edges=[leading_edge],
            method=fl.HeightBasedRefinement(value=0.001 * fl.u.m)
        ),
        # Surface refinement for general resolution
        fl.SurfaceRefinement(
            name="wing_surface",
            faces=[wing_surface],
            max_edge_length=0.05 * fl.u.m
        ),
        # Boundary layer refinement for wall regions
        fl.BoundaryLayer(
            name="wing_bl",
            faces=[wing_surface],
            first_layer_thickness=1e-5 * fl.u.m,
            growth_rate=1.2
        ),
        # Passive spacing refinement for interface region
        fl.PassiveSpacing(
            name="interface_region",
            type="projected",
            faces=[interface_surface]
        ),
        # Wake region refinement
        fl.UniformRefinement(
            name="wake_region",
            entities=[wake_box],
            spacing=0.1 * fl.u.m
        ),
        # Axisymmetric refinement for propeller region
        fl.AxisymmetricRefinement(
            name="propeller_region",
            entities=[prop_cylinder],
            spacing_axial=0.02 * fl.u.m,
            spacing_radial=0.01 * fl.u.m,
            spacing_circumferential=0.015 * fl.u.m
        ),
        # Geometry refinement for fine features
        fl.GeometryRefinement(
            name="fine_features_refinement",
            faces=[wing_surface, fuselage_surface],
            geometry_accuracy=0.001 * fl.u.m,
            preserve_thin_geometry=True
        )
    ]
)
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