# BluntStreamlines

VTKExamples/Cxx/VisualizationAlgorithms/BluntStreamlines

### Description

This example shows airflow around a blunt fin. This example consists of a wall with half a rounded fin projecting into the fluid flow. (Using arguments of symmetry, only half of the domain was modeled.) Twenty-five streamlines are released upstream of the fin. The boundary layer effects near the junction of the fin and wall are clearly evident from the streamlines. In this area, flow recirculation is apparent, as well as the reduced flow speed.

Info

See Figure 6-19 in Chapter 6 the VTK Textbook.

### Code

BluntStreamlines.cxx

    #include <vtkActor.h>
    #include <vtkCamera.h>
    #include <vtkLineSource.h>
    #include <vtkMultiBlockDataSet.h>
    #include <vtkMultiBlockPLOT3DReader.h>
    #include <vtkNamedColors.h>
    #include <vtkPointData.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSmartPointer.h>
    #include <vtkStreamTracer.h>
    #include <vtkStructuredGrid.h>
    #include <vtkStructuredGridGeometryFilter.h>
    #include <vtkStructuredGridOutlineFilter.h>

    int main(int argc, char *argv[] )
    {
      if (argc != 3)
      {
        std::cout << "Usage: " << argv[0] << " bluntfinxyz.bin bluntfinq.bin" << std::endl;
        return EXIT_FAILURE;
      }

      double range[2], c[3];
      double maxVelocity = 0.0, maxTime = 0.0;

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      vtkSmartPointer<vtkRenderer> aren =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renWin =
        vtkSmartPointer<vtkRenderWindow>::New();
      renWin->AddRenderer(aren);
      vtkSmartPointer<vtkRenderWindowInteractor> iren =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      iren->SetRenderWindow(renWin);

      std::string xyzFilename = argv[1];
      std::string qFilename = argv[2];

      vtkSmartPointer<vtkMultiBlockPLOT3DReader> reader =
        vtkSmartPointer<vtkMultiBlockPLOT3DReader>::New();
      reader->SetXYZFileName(xyzFilename.c_str());
      reader->SetQFileName(qFilename.c_str());
      reader->Update(); //force a read to occur

      vtkStructuredGrid *pd =
        vtkStructuredGrid::SafeDownCast(reader->GetOutput()->GetBlock(0));
      pd->GetCenter(c);
      if ( pd->GetPointData()->GetScalars() )
      {
        pd->GetPointData()->GetScalars()->GetRange(range);
      }
      if ( pd->GetPointData()->GetVectors() )
      {
        maxVelocity = pd->GetPointData()->GetVectors()->GetMaxNorm();
        maxTime = 20.0*pd->GetLength()/maxVelocity ;
      }

      vtkSmartPointer<vtkStructuredGridOutlineFilter> outlineF =
        vtkSmartPointer<vtkStructuredGridOutlineFilter>::New();
      outlineF->SetInputData(pd);

      vtkSmartPointer<vtkPolyDataMapper> outlineMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      outlineMapper->SetInputConnection(outlineF->GetOutputPort());

      vtkSmartPointer<vtkActor> outline =
        vtkSmartPointer<vtkActor>::New();
      outline->SetMapper(outlineMapper);
      outline->GetProperty()->SetColor(colors->GetColor3d("Moccasin").GetData());
      outline->GetProperty()->SetLineWidth(2.0);

    //
    // Some geometry for context
    //
      vtkSmartPointer<vtkStructuredGridGeometryFilter> wall =
        vtkSmartPointer<vtkStructuredGridGeometryFilter>::New();
      wall->SetInputData(pd);
      wall->SetExtent(0, 100, 0, 100, 0, 0);

      vtkSmartPointer<vtkPolyDataMapper> wallMap =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      wallMap->SetInputConnection(wall->GetOutputPort());
      wallMap->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> wallActor =
        vtkSmartPointer<vtkActor>::New();
      wallActor->SetMapper(wallMap);
      wallActor->GetProperty()->SetColor(colors->GetColor3d("Silver").GetData());

      vtkSmartPointer<vtkStructuredGridGeometryFilter> fin =
        vtkSmartPointer<vtkStructuredGridGeometryFilter>::New();
      fin->SetInputData(pd);
      fin->SetExtent(0,100,0,0,0,100);

      vtkSmartPointer<vtkPolyDataMapper> finMap =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      finMap->SetInputConnection(fin->GetOutputPort());
      finMap->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> finActor =
        vtkSmartPointer<vtkActor>::New();
      finActor->SetMapper(finMap);
      finActor->GetProperty()->SetColor(colors->GetColor3d("Silver").GetData());
    //
    // regular streamlines
    //
      vtkSmartPointer<vtkLineSource> line1 =
        vtkSmartPointer<vtkLineSource>::New();
      line1->SetResolution(25);
      line1->SetPoint1(-6.36, 0.25, 0.06);
      line1->SetPoint2(-6.36, 0.25, 5.37);

      vtkSmartPointer<vtkPolyDataMapper> rakeMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      rakeMapper->SetInputConnection(line1->GetOutputPort());

      vtkSmartPointer<vtkActor> rake1 =
        vtkSmartPointer<vtkActor>::New();
      rake1->SetMapper(rakeMapper);
      rake1->GetProperty()->SetColor(0.0,0.0,0.0);
      rake1->GetProperty()->SetLineWidth(5);

      vtkSmartPointer<vtkStreamTracer> streamers =
        vtkSmartPointer<vtkStreamTracer>::New();
      //  streamers->DebugOn();
      streamers->SetInputConnection(reader->GetOutputPort());
      streamers->SetSourceConnection(line1->GetOutputPort());
      streamers->SetMaximumPropagation(maxTime);
      streamers->SetInitialIntegrationStep(.2);
      streamers->SetMinimumIntegrationStep(.01);
      streamers->SetIntegratorType(2);
      streamers->Update();

      vtkSmartPointer<vtkPolyDataMapper> streamersMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      streamersMapper->SetInputConnection(streamers->GetOutputPort());
      streamersMapper->SetScalarRange(range);

      vtkSmartPointer<vtkActor> lines =
        vtkSmartPointer<vtkActor>::New();
      lines->SetMapper(streamersMapper);

      aren->AddActor(outline);
      aren->AddActor(wallActor);
      aren->AddActor(finActor);
      aren->AddActor(rake1);
      aren->AddActor(lines);
      aren->SetBackground(0.5,0.5,0.5);

      aren->ResetCamera();
      aren->GetActiveCamera()->Elevation(30.0);
      aren->GetActiveCamera()->Azimuth(30.0);
      aren->GetActiveCamera()->Dolly(1.2);
      aren->ResetCameraClippingRange();

      renWin->SetSize(640, 480);
      renWin->Render();

      // interact with data
      iren->Start();

      // Clean up

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(BluntStreamlines)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(BluntStreamlines MACOSX_BUNDLE BluntStreamlines.cxx )

    target_link_libraries(BluntStreamlines ${VTK_LIBRARIES})

### Download and Build BluntStreamlines

Click here to download BluntStreamlines and its CMakeLists.txt file. Once the tarball BluntStreamlines.tar has been downloaded and extracted,

    cd BluntStreamlines/build

If VTK is installed:

    cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

    cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

    make

and run it:

    ./BluntStreamlines

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.