# BluntStreamlines

VTKExamples/Python/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.

### Code

BluntStreamlines.py

    #!/usr/bin/env python

    import vtk

    def main():
        xyzFilename, qFilename = get_program_parameters()

        colors = vtk.vtkNamedColors()

        aren = vtk.vtkRenderer()
        renWin = vtk.vtkRenderWindow()
        renWin.AddRenderer(aren)
        iren = vtk.vtkRenderWindowInteractor()
        iren.SetRenderWindow(renWin)

        scalarRange = [0.0] * 2
        c = [0.0] * 3
        maxTime = 0.0

        reader = vtk.vtkMultiBlockPLOT3DReader()
        reader.SetXYZFileName(xyzFilename)
        reader.SetQFileName(qFilename)
        reader.Update()  # Force a read to occur.

        pd = reader.GetOutput().GetBlock(0)
        pd.GetCenter(c)
        if pd.GetPointData().GetScalars():
            pd.GetPointData().GetScalars().GetRange(scalarRange)
        if pd.GetPointData().GetVectors():
            maxVelocity = pd.GetPointData().GetVectors().GetMaxNorm()
            maxTime = 20.0 * pd.GetLength() / maxVelocity

        outlineF = vtk.vtkStructuredGridOutlineFilter()
        outlineF.SetInputData(pd)

        outlineMapper = vtk.vtkPolyDataMapper()
        outlineMapper.SetInputConnection(outlineF.GetOutputPort())

        outline = vtk.vtkActor()
        outline.SetMapper(outlineMapper)
        outline.GetProperty().SetColor(colors.GetColor3d("Moccasin"))
        outline.GetProperty().SetLineWidth(2.0)

        #
        # Some geometry for context
        #
        wall = vtk.vtkStructuredGridGeometryFilter()
        wall.SetInputData(pd)
        wall.SetExtent(0, 100, 0, 100, 0, 0)

        wallMap = vtk.vtkPolyDataMapper()
        wallMap.SetInputConnection(wall.GetOutputPort())
        wallMap.ScalarVisibilityOff()

        wallActor = vtk.vtkActor()
        wallActor.SetMapper(wallMap)
        wallActor.GetProperty().SetColor(colors.GetColor3d("Silver"))

        fin = vtk.vtkStructuredGridGeometryFilter()
        fin.SetInputData(pd)
        fin.SetExtent(0, 100, 0, 0, 0, 100)

        finMap = vtk.vtkPolyDataMapper()
        finMap.SetInputConnection(fin.GetOutputPort())
        finMap.ScalarVisibilityOff()

        finActor = vtk.vtkActor()
        finActor.SetMapper(finMap)
        finActor.GetProperty().SetColor(colors.GetColor3d("Silver"))
        #
        # regular streamlines
        #
        line1 = vtk.vtkLineSource()
        line1.SetResolution(25)
        line1.SetPoint1(-6.36, 0.25, 0.06)
        line1.SetPoint2(-6.36, 0.25, 5.37)

        rakeMapper = vtk.vtkPolyDataMapper()
        rakeMapper.SetInputConnection(line1.GetOutputPort())

        rake1 = vtk.vtkActor()
        rake1.SetMapper(rakeMapper)
        rake1.GetProperty().SetColor(0.0, 0.0, 0.0)
        rake1.GetProperty().SetLineWidth(5)

        streamers = vtk.vtkStreamTracer()
        # streamers.DebugOn()
        streamers.SetInputConnection(reader.GetOutputPort())
        streamers.SetSourceConnection(line1.GetOutputPort())
        streamers.SetMaximumPropagation(maxTime)
        streamers.SetInitialIntegrationStep(.2)
        streamers.SetMinimumIntegrationStep(.01)
        streamers.SetIntegratorType(2)
        streamers.Update()

        streamersMapper = vtk.vtkPolyDataMapper()
        streamersMapper.SetInputConnection(streamers.GetOutputPort())
        streamersMapper.SetScalarRange(scalarRange)

        lines = vtk.vtkActor()
        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 the data.
        iren.Start()

    def get_program_parameters():
        import argparse
        description = 'This example shows airflow around a blunt fin.'
        epilogue = '''
        '''
        parser = argparse.ArgumentParser(description=description, epilog=epilogue,
                                         formatter_class=argparse.RawDescriptionHelpFormatter)
        parser.add_argument('filename1', help='bluntfinxyz.bin.')
        parser.add_argument('filename2', help='bluntfinq.bin.')
        args = parser.parse_args()
        return args.filename1, args.filename2

    if __name__ == '__main__':
        main()