Fluid Mesh Generation Example

Overview

This tutorial provides the basic usage of fluid mesh generation, importing BREP, STEP, or STL format files, automatically generating volume meshes by passing mesh generation control parameters through JSON files.

Function Description

For the imported CFD geometry model with a far-field, a 3D HexCore hybrid mesh is generated in the outflow field region by defining appropriate material point locations.

Input: CFD model with an outflow field region; Output: 3D HexCore hybrid mesh.

Model Description

Basic JSON Configuration

The following is the basic JSON configuration. MeshingMethod is used to specify the generation algorithm and should be configured as "HexCore"; MaterialPoint is a coordinate in space, which can be any point in the external flow field; LocalSizeField is the size field and must be configured as AutomaticField type.

{
  "MeshSize": [
    {
      "CurvatureFactor": 0.2,
      "GrowthRate": 1.2,
      "MaxSize": 500,
      "MeshingMethod": "HexCore",
      "MaterialPoint":[-3458,3016.5,-1498],
      "MeshingDim": 3,
      "MinSize": 2,
      "SelectedEntities": []
   }
],
"LocalSizeField": {
    "BGField": 1,
    "AutomaticField": {
    "CurvatureFactor": 0.2,
    "NarrowRegionResolution2D":0.5,
    "GrowthRate": 1.2,
    "Tag": 1
    }
  },
"ThreadNum": 1
}

Complete Example

#include <nextmesh/NMAPIModel.hpp>
#include <nlohmann/json.hpp>
#include <occtio/OCCTTool.hpp>
#include <step/STEPTool.hpp>
#include <fstream>
 
using namespace AMCAX::NextMesh;
using namespace AMCAX;
 
int main()
{
    const std::string jsonPath = "./data/Canard.json";
    std::string pts_path = "./data/Canard_repair_fluid.step";
 
    AMCAX::TopoShape step_shape;
    AMCAX::STEP::STEPTool::Read(step_shape, pts_path);
 
    NMAPIModel nmapi;
    NMAPIModel::InitLogger();
    nmapi.ImportModel({ step_shape });
    nlohmann::json paraJ = nlohmann::json::parse(std::ifstream(jsonPath));
    nmapi.GenerateMesh(paraJ.dump());
    auto meshapi = nmapi.GetMesh();
    meshapi.Write("result", OutFileType::VTK);
}

Mesh generation results are shown below:

Click here to download the complete source code for the above examples. Please download it as needed for your learning purposes.