[Paraview] computing lift/drag coefficient/force in 2d using paraview

[Simone Crippa]

Hi,


I've been a silent reader of this thread. I'd also have a need for a
3D-surface variable integration filter. Since you offered to make your
filter available, now I thought I could knock on your door :-)

I've tried to gather a couple of filters/batch scripts for CFD
postprocessing and it seems to be pretty difficult. I am sure that some
of you list-subscribers out there have mastered many problems before and
it feels a bit dumb to "re-invent the wheel" on and on again ... I am
sure that somebody out there has written lots of remarkable/useful
filters (as you did) but it is impossible to have an overview.

I have been trying to find out something about a possible implementation
of line integral convolution, or something similar for visualizing skin
friction lines on 3d-surfaces (usually unstructured) and had no success.
Apart Jean Favre's 2D-planar, structured LEA filter I couldn't find
anything out there. 


I am not sure, but I think it would be of very high value to Paraview to
have e.g., a Wiki page, dedicated to gather these kind of filters, batch
scripts, user experiences about CFD postprocessing. I do not feel that
experienced to kick off such an effort, but maybe someone of the Kitware
team? 


Regards, Simone
 
 

On Tue, 2006-03-14 at 09:53 +0100, Theophane Foggia wrote:
> Hi,
> Because I had to compute flow rate across sections, torque values on
> body surfaces, etc, I have developed a filter called
> vtkIntegrateVariables which performs a discrete integration of a
> variable field (define on points of an unstructured mesh) over a
> surface. I give you an example of the way it works for a flow rate
> computation:
> - extract the surface
> - generate normals n
> - vtkCalculator: generate field V.n (where V is the velocity vector)
> - integrate with the vtkIntegrateVariables filter
> 
> The pipeline of the filter is the following:
> - check whether values are defined at points
> - pass values to cell (vtkPointDataToCellData)
> - loop over number of cells, compute cell_value*cell_area, sum
> - store the local integration values into an array
> - pass back to point data (vtkCellDataToPointData)
> - write the result (sum of the local integrations) into a file
> I have compared the results of torque and flow rate integration with
> CFX5.7-Post and it gives extremely good results. I have used it for 3D
> surface integration but it should work for 2D line. If you wish to use
> it, please let me know and I will send it to you. An option for cell
> data input has then to be added.
> I would be glad to contribute to paraview with this filter if needed.
> In such a case I will modified it so that it can handle different
> kinds of input data type. Just let me know.
> Theophane
> 
> -- 
> Theophane Foggia
> CSCS - Swiss National Supercomputing Centre   | Tel: +41 (91) 610.82.14
> via Cantonale, 6928 Manno, Switzerland        | Fax: +41 (91) 610.82.82
> 
> 
> Ben Tay wrote: 
> > hi,
> >  
> > i need to compute lift/drag coefficient/force in 2d for flow past
> > cylinder/airfoil etc. my output data is single structured c-grid
> > with cell center velocities/pressure. I am trying to explore
> > different software to find out which is better. Has anybody tried
> > using paraview. Is it easy? thanks. 
> > 
> > ____________________________________________________________________
> > 
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> >   
> 
> 
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-- 
Simone Crippa
Research assistant, Dipl.-Ing.
Royal Institute of Technology (KTH)
Aeronautical and Vehicle Engineering
Division of Aerodynamics
Teknikringen 8
SE-10044 Stockholm, Sweden
+46 (0)8 790 646