[vtkusers] Problem when tracing streamlines (VTK 4.2.2) - 2D mesh

[David ANDRE (SOGETI)]

Hi everybody

I've got a problem when tracing streamlines (VTK 4.2.2)

 

My shape is a 2D base representing a plane wing (Triangle based -
Unstructured-grid). My streamlines should formalize friction vectors running
along the wall (upper side) and expected to stop onto the trailing edge.

 

I use a StreamTracer objet to realize it. Streamlines are "well" drawn, but
I can observe some inconsistencies, 

 

In the Doxygen documentation related to VTK 4.2.2, it is mentionned that "if
the dataset contains 2D cells such as polygons or triangles, the integration
is constrained to lie on the surface defined by the 2D cells." 

 

I observe on my results that my streamlines go out of the limits of my
defined 2D grid and don't lie exactly on the surface. Sometimes it goes
inside or outside the surface as if it was a volumic domain (3D base). When
arriving on the trailing edge, despite of being stopped the streams go
further and continue in the space around.

 

Does anyone have any idea ?

 

Thanks for your help

Regards. David

 

 

My source code is like that : 

 

            vtkStreamTracer * pStreamTracer = vtkStreamTracer::New();   

            

            ... Initisalized with an unstructured grid ...

            

            pStreamTracer->SetInitialIntegrationStepUnitToCellLengthUnit ();

            pStreamTracer->SetInitialIntegrationStep( step );

            pStreamTracer->SetIntegratorType( vtkStreamSolverType );

            pStreamTracer->ComputeVorticityOff ();

                        

        // Structure to stock starting points

        vtkPolyData *pPolyData = vtkPolyData::New();

        pPolyData->SetPoints( pPoints );

        pPoints->Delete();

 

        // Memorizing starting points

        pStreamTracer->SetSource( pPolyData );

        pPolyData->Delete();

 

        // Propagation parameters

        pStreamTracer->SetMaximumPropagationUnitToCellLengthUnit () ;

        pStreamTracer->SetMaximumPropagation ( MaxIterationNb  );

 

        // Number of Steps

        pStreamTracer->SetMaximumNumberOfSteps (MaxIterationNb);

                        

                        //  Generation

        pStreamTracer->Update();

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20090312/25e3caa8/attachment.htm>