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

[Theophane Foggia]

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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