Mesh Quality Example

Example Usage

AMCAX_API double ComputeQuality(const NMMeshElem        &elem,
                                const QualityType        qtye,
                                const CommercialSoftware cstye);

Parameter Type Descriptions

NMMeshElem

Element types include linear elements: triangles, quadrilaterals, tetrahedrons, pyramids, prisms, and hexahedrons.

Tri_3

Quad_4

Tet_4

Pyramid_5

Prism_6

Hex_8

QualityType

Quality metrics include most commercial software quality indicators:

MinLength	Minimum Length	MaxLength	Maximum Length	MinHeight	Minimum Height	MinNormalizedHeight	Minimum Normalized Height
CharacteristicLength	Characteristic Length	ElementQuality	Element Quality (ANSYS)	SkewnessByVolume	Volume-based Skewness	SkewnessByEquiangular	Angle-based Skewness
MaxAngle2d	2D Maximum Angle	MinAngle2d	2D Minimum Angle	JacobianRatioByCorner	Corner-based Jacobian Ratio	JacobianRatioByGauss	Gauss-point-based Jacobian Ratio
AspectRatio	Aspect Ratio	Collapse	Collapse Value	WarpingAngle	Warping Angle	WarpingFactor	Warping Factor
ChordalDeviation	Chordal Deviation	Taper	Taper Ratio	MaxDihedraAngle	Maximum Dihedral Angle	MinDihedraAngle	Minimum Dihedral Angle

CommercialSoftware

Commercial software types with independent quality metric calculation methods: HyperMesh, ANSYS, Fluent, Nastran.

HyperMesh

ANSYS

Fluent

Nastran

Metric Value Ranges

Optimal/worst values for each quality metric:

Quality Metric	[worst, best]
Skewness (angle)	[90°, 0°]
Skewness (value)	[1, 0]
Jacobian	[-1, 1]
Aspect Ratio	[inf, 1]
Warping (angle)	[pi, 0]
Warping factor (value)	[inf, 0]
Interior Angles	Tri: Max angle: [180°, 60°] Min angle: [0°, 60°] Quad: Max angle: [180°, 90°] Min angle:[0°, 90°]
Collapse	[0, 1]
Taper	[1, 0]
Element Quality	[0, 1]

Business Metrics Comparison Table

HyperMesh (Shells)
Aspect Ratio	Skew	Chordal Deviation	Warpage	Tri minimum angle	Tri maximum angle	Quad minimum angle	Quad maximum angle	Minimum length	Maximum length

HyperMesh (Solid)
Aspect Ratio	Skew	Volumetric Skewness	Jacobian	Tet collapse	Equia skew	Minimum angle	Maximum angle	Minimum length

ANSYS (Shells)
Aspect Ratio	Skewness	Warping	Jacobian	Minimum angle	Maximum angle	Characteristic Length	Minimum length	Element Quality	Parallel Deviation

ANSYS (Solid)
Aspect Ratio	Warping	Jacobian	Collapse	Characteristic Length	Min Height	Element Quality	Parallel Deviation

Fluent (Shells)
Aspect Ratio	Skewness	Warp

Fluent (Solid)
Aspect Ratio	Skewness	Warp	Dihedral Angle

Nastran (Shells)
Aspect Ratio	Skewness	Warping	Taper	Jacobian	Minimum angle	Maximum angle	Characteristic Length	Minimum length

Nastran (Solid)
Aspect Ratio	Warping	Jacobian	Collapse	Characteristic Length	Min Height

Complete Example

A complete example demonstrating how to obtain area skewness for 2D triangular surface meshes and volume skewness for 3D tetrahedral volume meshes, analyzed using Fluent commercial software:

#include <fstream>
#include <nlohmann/json.hpp>
#include <nextmesh/NMAPIModel.hpp>
#include <set>
#include <occtio/OCCTTool.hpp>
 
using namespace AMCAX::NextMesh;
 
void Quality()
{
    const std::string jsonPath = "./data/test.json";
 
    NMAPIModel nmapi;
    NMAPIModel::InitLogger();
    AMCAX::TopoShape shape;
    AMCAX::OCCTIO::OCCTTool::Read(shape, "./data/test.brep");
    std::vector<NMShape>shapes = { shape };
    nmapi.ImportModel(shapes);
 
    std::vector<NMEntity> ent_d2, ent_d3;
    nmapi.GetEntities(ent_d2, DimType::D2);
    nmapi.GetEntities(ent_d3, DimType::D3);
 
    nlohmann::json paraJ = nlohmann::json::parse(std::ifstream(jsonPath));
    nmapi.GenerateMesh(paraJ.dump());
    auto meshapi = nmapi.GetMesh();
 
    for (auto entf : ent_d2)
    {
        auto ec = meshapi.EntityGetElementCount(entf);
        for (size_t i = 0; i < ec; i++)
        {
            auto elem = meshapi.EntityGetElementByIndex(entf, i);
            double quality = 1.0;
            if (meshapi.ElementGetType(elem) == ElemType::Tri_3)
            {
                quality = meshapi.ComputeQuality(
                    elem,
                    QualityType::SkewnessByVolume,
                    CommercialSoftware::Fluent
                );
            }
        }
    }
 
    for (auto entf : ent_d3)
    {
        auto ec = meshapi.EntityGetElementCount(entf);
        for (size_t i = 0; i < ec; i++)
        {
            auto elem = meshapi.EntityGetElementByIndex(entf, i);
            double quality = 1.0;
            if (meshapi.ElementGetType(elem) == ElemType::Tet_4)
            {
                quality = meshapi.ComputeQuality(
                    elem,
                    QualityType::SkewnessByVolume,
                    CommercialSoftware::Fluent
                );
            }
        }
    }
}
 
int main()
{
    Quality();
}

Click here example04 to get the full source code of the Mesh Quality example, you can download it according to your learning needs.