Implementation of Anisotropic Mesh Refinement in OpenFOAM Jonas - - PowerPoint PPT Presentation

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implementation of anisotropic mesh refinement in openfoam

Implementation of Anisotropic Mesh Refinement in OpenFOAM Jonas - - PowerPoint PPT Presentation

Dec 05, 2022 174 likes •643 views

Implementation of Anisotropic Mesh Refinement in OpenFOAM Jonas Karlsson Hydrodynamics Group Department of Shipping and Marine Technology Chalmers University of Technology Gteborg, Sweden November 13, 2012 Introduction Implementation

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Implementation of Anisotropic Mesh Refinement in OpenFOAM

Jonas Karlsson

Hydrodynamics Group Department of Shipping and Marine Technology Chalmers University of Technology Göteborg, Sweden

November 13, 2012

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About this work

MSc. thesis in Computer Science

Employee at Shipping and Marine Technology

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Adaptive Mesh Refinement (AMR)

Refine (split) cells with greatest error Anisotropic refinement. Refine in one direction

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OpenFOAM

Supports isotropic (not anisotropic) AMR Provides:

Face remover (for unrefinement) Synchronization (sending/receiving parts of mesh) Topology tools (polyTopoChange for adding/removing points cells and faces)

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Application components

Refinement-engine Selects cells to refine Mesh-cutter Executes topological changes for ansiotropic split Refinement-tree Stores the refinement changes Note: Only for hexahedra.

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Refinement-tree

Enables unrefinement Criteria – store the refinement-changes and be redistributable.

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Refinement-tree example

Domain Refinement-tree

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Refinement-tree example

Domain Refinement-tree

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Mesh Cutter

Used for cutting/splitting cells anisotropically For every cell store its corner points Split between predetermined pairs of points

4 5 7 6 1 2 3

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Mesh Cutter

Used for cutting/splitting cells anisotropically For every cell store its corner points Split between predetermined pairs of points

4 5 7 6 1 2 3

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Mesh Cutter

Used for cutting/splitting cells anisotropically For every cell store its corner points Split between predetermined pairs of points

4 5 7 6 1 2 3

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Mesh Cutter (Consistency)

Hanging node:

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Mesh Cutter (Consistency)

Hanging node: ”Two-to-one” rule. 2D: every side of a cell has at most two edges, 3D: every side of a cell has at most two faces.

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Mesh Cutter (Consistency)

Hanging node: ”Two-to-one” rule. 2D: every side of a cell has at most two edges, 3D: every side of a cell has at most two faces. Refered to as a Consistent mesh.

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Mesh Cutter (Splits)

Allowed:

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Mesh Cutter (Splits)

Allowed: Disallowed:

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Mesh Cutter (Splits)

Constraint: For a face to be splittable it needs to contain four corner points from its neighbour

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Mesh Cutter (Spreading)

Original domain Shaded cell marked for refinement Spreading algorithm marks big cell Refining all cells not restricted Repeat

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Mesh Cutter (Spreading)

Original domain Shaded cell marked for refinement Spreading algorithm marks big cell Refining all cells not restricted Repeat

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Mesh Cutter (Spreading)

Original domain Shaded cell marked for refinement Spreading algorithm marks big cell Refining all cells not restricted Repeat

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Mesh Cutter (Spreading)

Original domain Shaded cell marked for refinement Spreading algorithm marks big cell Refining all cells not restricted Repeat

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Mesh Cutter (Spreading)

Original domain Shaded cell marked for refinement Spreading algorithm marks big cell Refining all cells not restricted Repeat

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Refinement-engine flow graph

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Refinement-engine collaboration diagram

dynamicRefineFvMeshHexRef2 dynamicFvMesh hexRef2 meshCutter_ refinementTree refTree_

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Spreading example

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Spreading example

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Spreading example

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Spreading example

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Spreading example

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Spreading example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Parallel example

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Questions and comments