v2406: New and improved pre-processing
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The new createViewFactors utility creates patch-to-patch view factors for the viewFactor radiation model. This serves as a potential replacement for the current viewFactorsGen utility. Users can select the models used to both construct the face-to-face addressing and how the view factors are calculated, i.e.
Ray generation:
- voxel: space divided into uniform voxels
- ...further methods will be released in the near future
View factor calculation:
- viewFactorHottel: 2D method based on Hottel's crossed strings method
- viewFactor2AI: double area integral
- viewFactor2LI: double line integral
Instead of testing all faces against all faces, i.e. using an N^2 algorithm (viewFactorsGen), the user supplies the number of rays to seed per face. These are issued uniformly across a hemisphere. Hence, the results are more approximate than the previous utility, but can now be applied to production cases with much improved performance. Examples:
2D: linearly distributed in the range 0-180 deg (2D). Example using 300 rays, coloured by ray index:
3D: distributed using a hemisphere of equally spaced points. Example using 1024 rays
Note that this is currently in beta-level and is likely to change in the near future.
Tutorial
- TBA
Source code
Gitlab
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The renumberMesh utility has been extended to include new options and functionality, e.g.
- Use -dry-run with the -write-maps option to visualize the before/after effects of renumbering (creates a VTK file) without making any changes.
- Use the -no-fields option to renumber the mesh only without affecting the fields. This is useful and much faster when the input fields are uniform, and the -overwrite option is specified.
The new -renumber-method and -renumber-coeffs options permit use of renumberMesh without needing to edit a separate file, e.g.
- renumberMesh -renumber-method CuthillMcKee
- renumberMesh -renumber-method RCM (ie, Reverse Cuthill-McKee)
- renumberMesh -renumber-method random
- renumberMesh -renumber-method none (very special case!)
For methods requiring coefficients, these can be specified with the -renumber-coeffs option. Here are four different ways to specify reverse Cuthill-McKee:
- renumberMesh -renumber-method RCM
- renumberMesh -renumber-method CuthillMcKee -renumber-coeffs 'reverse true;'
- `renumberMesh -renumber-coeffs 'method CuthillMcKee; reverse true;'
- `renumberMesh -renumber-coeffs 'method RCM;'
As can be seen from these examples, the -renumber-coeffs correspond to OpenFOAM dictionary content, which allows relatively complex content:
renumberMesh \
renumber-method spring \
renumber-coeffs 'maxCo 0.1; maxIter 1000; freezeFraction 0.99;'
In addition to the renumbering methods, renumberMesh now supports a -decompose method, applied before renumbering. This can be used as a replacement for parallel renumbering to simplify workflows.
Tutorial
Source code
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snappyHexMesh aims to produce identical meshes when running in both serial and parallel modes. In this release two synchronisations were addressed:
- when using the slower-than-2:1 refinement, i.e. nCellsBetweenLevels > 1
- when detecting cells with all points on the boundary. These were treated differently if the points were on processor boundaries.
Tutorials
- N/A
Source code
- $FOAM_SRC/dynamicMesh/polyTopoChange/polyTopoChange/hexRef8/hexRef8.C
- $FOAM_SRC/mesh/snappyHexMesh/meshRefinement/meshRefinementProblemCells.C
Gitlab
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The surfaceInertia utility now emits information about the average area normal, which can be useful for various orientation-related geometry or mesh manipulations during pre- and post-processing:
- combine with linearDirection to achieve better extrusion results.
- orientation of transformations, blockMesh, result projections, ...
Source code
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More utilities now support overlapping zones of points, faces, and cells. In previous releases this was only supported in decomposePar and specific solvers.
- redistributePar : full support
- subsetMesh : full support
- polyTopoChange : extended routines to add/modify mesh elements into multiple zones instead of a single one
- polyMesh : additional interrogation routine to check the zones an element is in
This adds to the existing support for constructing zones directly inside topoSet using any source, e.g.:
name c0;
type cellZoneSet;
action new;
source boxToCell;
box (0.04 0 0)(0.06 100 100);
This will directly generate a cellZone c0 from a rectangular section of the mesh.
Source code
Tutorial
Gitlab
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Geometric selection sources in topoSet now support optional transformations for cell, face centre or point locations before the selection is applied. Transformations take the form of solidBodyMotionFunctions, e.g.
name c0;
type cellSet;
action new;
source boxToCell;
box (0.04 0 0)(0.06 100 100);
solidBodyMotionFunction rotatingMotion;
rotatingMotionCoeffs
{
// coefficients
}
This is useful for simulating moving sources, e.g. in <constant>/fvOptions:
selectionMode geometric;
selection
{
cyl1
{
action use;
source cylinder;
point1 (0.05 0.03 -1); // beg point on cylinder axis
point2 (0.05 0.03 1); // end point on cylinder axis
radius 0.003;
solidBodyMotionFunction oscillatingLinearMotion;
oscillatingLinearMotionCoeffs
{
// coefficients
amplitude (0 0.02 0);
omega 0.7; // rad/s
}
}
}
Source code
Tutorial
Gitlab
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The transformPoints and surfaceTransformPoints utilities are used to transform mesh (or surface) points. The new option -cylToCart applies a cylindrical-to-Cartesian transformation to aid cylindrical mesh generation.
The example below is from the new tutorial $FOAM_TUTORIALS/incompressible/pimpleFoam/RAS/axialTurbine_rotating_oneBlade where the left image shows the components constructed in cylindrical coordinates, and the right image the sections after transformation to Cartesian coordinates.
Tutorial
Source code
Gitlab
Attribution
- Thanks to Håkan Nilsson for contributing the transformation code