Re: [Paraview] Calculation of Lambda2 using ParaView...

[Stefan Melber]

Hi Andy,

ok - try to do the job with a programmable filter:


importnumpyasnp

fromnumpyimportlinalg asLA

fromparaview.numpy_supportimportvtk_to_numpy

input0 =inputs[0]

# Test NumPy

w, v =LA.eig(np.diag((1, 2, 3)))

printw

printv

npArr =vtk_to_numpy(input0.PointData["val"])




The test with the eig-function works fine. However - i have to convert 
the val-Tensor from VTK to NumPy to work with NumPy. I use therefore the 
vtk_to_numpy function - but it gives




Traceback (most recent call last):

File "", line 22, in 

File "", line 19, in RequestData

File 
"/opt/PARAVIEW_5_4_0_OpenGL2/ParaView-v5.4.0.bin/lib/site-packages/paraview/numpy_support.py", 
line 213, in vtk_to_numpy


typ = vtk_array.GetDataType()

AttributeError: 'VTKCompositeDataArray' object has no attribute 
'GetDataType'


[ 1. 2. 3.]

[[ 1. 0. 0.]

[ 0. 1. 0.]

[ 0. 0. 1.]]


What did i wrong?

  Stefan



Hi,

The best way to do this would be in a programmable filter. I'm 
guessing numpy has some method to compute eigenvalues for 
non-symmetric matrices. Beyond that adding the capability to the 
Python calculator or some other filter would be needed.




On Tue, Jun 13, 2017 at 3:35 AM, Stefan Melber > wrote:


Hi Andy,

i think i found the reason: i need the computation of
(unsymmetrical) eigenvalues for lambda2 - however it seems that
the function "eingenvalue" calculates only symmetric ones (see

https://www.paraview.org/ParaView/Doc/Nightly/www/py-doc/paraview.vtk.numpy_interface.algorithms.html

).
How can i calculate the unsymmetric ones with ParaView?

Best regards,

 Stefan



Hi,

Maybe compute each portion manually and check that against the
correct values. Also, verifying the gradient calculation is
correct is another thing to look at. If the grid isn't specified
properly then the gradient operation will likely be wrong.

On Fri, Jun 9, 2017 at 8:46 AM, Stefan Melber
mailto:stefan.mel...@dlr.de>> wrote:

Hi,


for vortex-detection i (tried) to calculate the
lambda2-criterion (see e.g.
https://en.wikipedia.org/wiki/Lambda2_method
) with
ParaView. The way of calculation is based on this link

http://www.iesensor.com/blog/2016/01/24/using-paraview-to-visualise-vorticity-lambda2-vorticity-q-criterion/

.

However - the results are a kind of "wrong" - see attached
pictures: l2_solver.png shows what the flow solver writes out
for lambda2, l2_paraview.png shows what calculated with the
algorithm below.

Calculation of lambda2:

D = Gradients = [d_ij]
S = strain(Vel)

S = (D + D^T)/2
Omega = (D - D^T)/2

lambda = EigenValue_of(S^2 + Omega^2)
   = EigenValue_of(S^2 + (D - S)^2)
   = EigenValue_of(S^2 + (Gradients - strain(vel))^2)

lambda2 = lambda_Y

and in ParaView this mean

o Vector of velocity with "Calculator".: Vel
= iHat*x_velocity+jHat*y_velocity+kHat*z_velocity
o Gradients of Vel with "GradientOfUnstructuredDataSet":
switch on "compute gradient" and name it "Gradients"
o Calculate lambda with "PythonCalculator".:
lambda = eigenvalue(strain(Vel)**2+(Gradients - strain(Vel))**2)
o Caluclate lambda2 with Calculator:
lambda2 = lambda_Y



Does anyone see the error why the calculation of lambda2 with
ParaView does not work?

Remark: i contacted the author of the blog above already -
seems he never tested his calculation and has no idea what is
"wrong".

Stefan





 _/ *Dr. Stefan Melber-Wilkending*
   _/_/
 _/  _/ Deutsches Zentrum für Luft-
 _/_/_/_/_/_/_/_/_/_/ und Raumfahrt e.V. (DLR)
   _/_/_/ _/
 _/_/_/_/ German Aerospace Center
   _/_/_/_/_/_/_/_/_/_/ Institute of Aerodynamics
 _/  _/  _  _ and Flow Technology
 _/_/   | \ |  |_| Transport Aircraft Branch
 _/ |_/ |_ | \
Lilienthalplatz 7
 Fields of activities: 38108 Braunschweig
Germany
 o Numerical Windtunnel Simulation
 o Aero-Acoustic Windtunnel Design Phone : +49 531/295-2836

 o Numerical Optimization Fax. .: +49 531/295-2914

 o Visualization Techniques
 o High-Lift Aerodynamics Email : stefan.mel...@dlr.de

Re: [Paraview] Calculation of Lambda2 using ParaView...

[Andy Bauer]

Hi,

The best way to do this would be in a programmable filter. I'm guessing
numpy has some method to compute eigenvalues for non-symmetric matrices.
Beyond that adding the capability to the Python calculator or some other
filter would be needed.



On Tue, Jun 13, 2017 at 3:35 AM, Stefan Melber  wrote:

> Hi Andy,
>
> i think i found the reason: i need the computation of (unsymmetrical)
> eigenvalues for lambda2 - however it seems that the function "eingenvalue"
> calculates only symmetric ones (see https://www.paraview.org/
> ParaView/Doc/Nightly/www/py-doc/paraview.vtk.numpy_
> interface.algorithms.html). How can i calculate the unsymmetric ones with
> ParaView?
>
> Best regards,
>
>  Stefan
>
>
> Hi,
>
> Maybe compute each portion manually and check that against the correct
> values. Also, verifying the gradient calculation is correct is another
> thing to look at. If the grid isn't specified properly then the gradient
> operation will likely be wrong.
>
> On Fri, Jun 9, 2017 at 8:46 AM, Stefan Melber 
> wrote:
>
>> Hi,
>>
>>
>> for vortex-detection i (tried) to calculate the lambda2-criterion (see
>> e.g. https://en.wikipedia.org/wiki/Lambda2_method) with ParaView. The
>> way of calculation is based on this link http://www.iesensor.com/blog/2
>> 016/01/24/using-paraview-to-visualise-vorticity-lambda2-vort
>> icity-q-criterion/.
>>
>> However - the results are a kind of "wrong" - see attached pictures:
>> l2_solver.png shows what the flow solver writes out for lambda2,
>> l2_paraview.png shows what calculated with the algorithm below.
>>
>> Calculation of lambda2:
>>
>> D = Gradients = [d_ij]
>> S = strain(Vel)
>>
>> S = (D + D^T)/2
>> Omega = (D - D^T)/2
>>
>> lambda = EigenValue_of(S^2 + Omega^2)
>>= EigenValue_of(S^2 + (D - S)^2)
>>= EigenValue_of(S^2 + (Gradients - strain(vel))^2)
>>
>> lambda2 = lambda_Y
>>
>> and in ParaView this mean
>>
>> o Vector of velocity with "Calculator".: Vel =
>> iHat*x_velocity+jHat*y_velocity+kHat*z_velocity
>> o Gradients of Vel with "GradientOfUnstructuredDataSet": switch on
>> "compute gradient" and name it "Gradients"
>> o Calculate lambda with "PythonCalculator".: lambda =
>> eigenvalue(strain(Vel)**2+(Gradients - strain(Vel))**2)
>> o Caluclate lambda2 with Calculator: lambda2 =
>> lambda_Y
>>
>>
>>
>> Does anyone see the error why the calculation of lambda2 with ParaView
>> does not work?
>>
>> Remark: i contacted the author of the blog above already - seems he never
>> tested his calculation and has no idea what is "wrong".
>>
>> Stefan
>>
>>
>>
>> 
>>
>>  _/ *Dr. Stefan Melber-Wilkending*
>>_/_/
>>  _/  _/ Deutsches Zentrum für Luft-
>>  _/_/_/_/_/_/_/_/_/_/ und Raumfahrt e.V. (DLR)
>>_/_/_/_/
>>  _/_/_/_/ German Aerospace Center
>>_/_/_/_/_/_/_/_/_/_/  Institute of Aerodynamics
>>  _/  _/  _  _   and Flow Technology
>>  _/_/   | \ |  |_|   Transport Aircraft Branch
>>  _/ |_/ |_ | \
>>  Lilienthalplatz 7
>>  Fields of activities:  38108 Braunschweig
>>  Germany
>>  o Numerical Windtunnel Simulation
>>  o Aero-Acoustic Windtunnel DesignPhone : +49 531/295-2836
>> <%28531%29%20295-2836>
>>  o Numerical Optimization Fax. .: +49 531/295-2914
>> <%28531%29%20295-2914>
>>  o Visualization Techniques
>>  o High-Lift Aerodynamics   Email : stefan.mel...@dlr.de
>>  o Glider-Aerodynamics  Web ..: http://www.dlr.de/AS
>>
>>
>> 
>>
>>
>> ___
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the ParaView Wiki at:
>> http://paraview.org/Wiki/ParaView
>>
>> Search the list archives at: http://markmail.org/search/?q=ParaView
>>
>> Follow this link to subscribe/unsubscribe:
>> http://public.kitware.com/mailman/listinfo/paraview
>>
>>
>
>
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Re: [Paraview] Calculation of Lambda2 using ParaView...

[Stefan Melber]

Hi Andy,

i think i found the reason: i need the computation of (unsymmetrical) 
eigenvalues for lambda2 - however it seems that the function 
"eingenvalue" calculates only symmetric ones (see 
https://www.paraview.org/ParaView/Doc/Nightly/www/py-doc/paraview.vtk.numpy_interface.algorithms.html). 
How can i calculate the unsymmetric ones with ParaView?


Best regards,

 Stefan



Hi,

Maybe compute each portion manually and check that against the correct 
values. Also, verifying the gradient calculation is correct is another 
thing to look at. If the grid isn't specified properly then the 
gradient operation will likely be wrong.


On Fri, Jun 9, 2017 at 8:46 AM, Stefan Melber > wrote:


Hi,


for vortex-detection i (tried) to calculate the lambda2-criterion
(see e.g. https://en.wikipedia.org/wiki/Lambda2_method
) with ParaView. The
way of calculation is based on this link

http://www.iesensor.com/blog/2016/01/24/using-paraview-to-visualise-vorticity-lambda2-vorticity-q-criterion/

.

However - the results are a kind of "wrong" - see attached
pictures: l2_solver.png shows what the flow solver writes out for
lambda2, l2_paraview.png shows what calculated with the algorithm
below.

Calculation of lambda2:

D = Gradients = [d_ij]
S = strain(Vel)

S = (D + D^T)/2
Omega = (D - D^T)/2

lambda = EigenValue_of(S^2 + Omega^2)
   = EigenValue_of(S^2 + (D - S)^2)
   = EigenValue_of(S^2 + (Gradients - strain(vel))^2)

lambda2 = lambda_Y

and in ParaView this mean

o Vector of velocity with "Calculator".: Vel =
iHat*x_velocity+jHat*y_velocity+kHat*z_velocity
o Gradients of Vel with "GradientOfUnstructuredDataSet": switch on
"compute gradient" and name it "Gradients"
o Calculate lambda with "PythonCalculator".: lambda =
eigenvalue(strain(Vel)**2+(Gradients - strain(Vel))**2)
o Caluclate lambda2 with Calculator: lambda2 =
lambda_Y



Does anyone see the error why the calculation of lambda2 with
ParaView does not work?

Remark: i contacted the author of the blog above already - seems
he never tested his calculation and has no idea what is "wrong".

Stefan





 _/ *Dr. Stefan Melber-Wilkending*
   _/_/
 _/  _/ Deutsches Zentrum für Luft-
 _/_/_/_/_/_/_/_/_/_/ und Raumfahrt e.V. (DLR)
   _/_/_/ _/
 _/_/_/_/ German Aerospace Center
   _/_/_/_/_/_/_/_/_/_/ Institute of Aerodynamics
 _/  _/  _  _   and Flow Technology
 _/_/   | \ |  |_|   Transport Aircraft Branch
 _/ |_/ |_ | \
Lilienthalplatz 7
 Fields of activities:  38108 Braunschweig
Germany
 o Numerical Windtunnel Simulation
 o Aero-Acoustic Windtunnel DesignPhone : +49 531/295-2836

 o Numerical Optimization Fax. .: +49 531/295-2914

 o Visualization Techniques
 o High-Lift Aerodynamics   Email : stefan.mel...@dlr.de

 o Glider-AerodynamicsWeb ..: http://www.dlr.de/AS




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Re: [Paraview] Calculation of Lambda2 using ParaView...

[Stefan Melber]

Hi Andy,

unfortunately my comparison values (correct lambda2) does not have an 
results in between to compare with. Regarding the gradients i am sure 
they are ok. For this dataset i calculated other stuff based on the 
gradients and thats ok. Maybe the error is in the syntax or the usage of 
the eigenvalues-function - will check there ...


Stefan

Hi,

Maybe compute each portion manually and check that against the correct 
values. Also, verifying the gradient calculation is correct is another 
thing to look at. If the grid isn't specified properly then the 
gradient operation will likely be wrong.


On Fri, Jun 9, 2017 at 8:46 AM, Stefan Melber > wrote:


Hi,


for vortex-detection i (tried) to calculate the lambda2-criterion
(see e.g. https://en.wikipedia.org/wiki/Lambda2_method
) with ParaView. The
way of calculation is based on this link

http://www.iesensor.com/blog/2016/01/24/using-paraview-to-visualise-vorticity-lambda2-vorticity-q-criterion/

.

However - the results are a kind of "wrong" - see attached
pictures: l2_solver.png shows what the flow solver writes out for
lambda2, l2_paraview.png shows what calculated with the algorithm
below.

Calculation of lambda2:

D = Gradients = [d_ij]
S = strain(Vel)

S = (D + D^T)/2
Omega = (D - D^T)/2

lambda = EigenValue_of(S^2 + Omega^2)
   = EigenValue_of(S^2 + (D - S)^2)
   = EigenValue_of(S^2 + (Gradients - strain(vel))^2)

lambda2 = lambda_Y

and in ParaView this mean

o Vector of velocity with "Calculator".: Vel =
iHat*x_velocity+jHat*y_velocity+kHat*z_velocity
o Gradients of Vel with "GradientOfUnstructuredDataSet": switch on
"compute gradient" and name it "Gradients"
o Calculate lambda with "PythonCalculator".: lambda =
eigenvalue(strain(Vel)**2+(Gradients - strain(Vel))**2)
o Caluclate lambda2 with Calculator: lambda2 =
lambda_Y



Does anyone see the error why the calculation of lambda2 with
ParaView does not work?

Remark: i contacted the author of the blog above already - seems
he never tested his calculation and has no idea what is "wrong".

Stefan





 _/ *Dr. Stefan Melber-Wilkending*
   _/_/
 _/  _/ Deutsches Zentrum für Luft-
 _/_/_/_/_/_/_/_/_/_/ und Raumfahrt e.V. (DLR)
   _/_/_/ _/
 _/_/_/_/ German Aerospace Center
   _/_/_/_/_/_/_/_/_/_/ Institute of Aerodynamics
 _/  _/  _  _   and Flow Technology
 _/_/   | \ |  |_|   Transport Aircraft Branch
 _/ |_/ |_ | \
Lilienthalplatz 7
 Fields of activities:  38108 Braunschweig
Germany
 o Numerical Windtunnel Simulation
 o Aero-Acoustic Windtunnel DesignPhone : +49 531/295-2836

 o Numerical Optimization Fax. .: +49 531/295-2914

 o Visualization Techniques
 o High-Lift Aerodynamics   Email : stefan.mel...@dlr.de

 o Glider-AerodynamicsWeb ..: http://www.dlr.de/AS




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Re: [Paraview] Calculation of Lambda2 using ParaView...

[Andy Bauer]

Hi,

Maybe compute each portion manually and check that against the correct
values. Also, verifying the gradient calculation is correct is another
thing to look at. If the grid isn't specified properly then the gradient
operation will likely be wrong.

On Fri, Jun 9, 2017 at 8:46 AM, Stefan Melber  wrote:

> Hi,
>
>
> for vortex-detection i (tried) to calculate the lambda2-criterion (see
> e.g. https://en.wikipedia.org/wiki/Lambda2_method) with ParaView. The way
> of calculation is based on this link http://www.iesensor.com/blog/
> 2016/01/24/using-paraview-to-visualise-vorticity-lambda2-
> vorticity-q-criterion/.
>
> However - the results are a kind of "wrong" - see attached pictures:
> l2_solver.png shows what the flow solver writes out for lambda2,
> l2_paraview.png shows what calculated with the algorithm below.
>
> Calculation of lambda2:
>
> D = Gradients = [d_ij]
> S = strain(Vel)
>
> S = (D + D^T)/2
> Omega = (D - D^T)/2
>
> lambda = EigenValue_of(S^2 + Omega^2)
>= EigenValue_of(S^2 + (D - S)^2)
>= EigenValue_of(S^2 + (Gradients - strain(vel))^2)
>
> lambda2 = lambda_Y
>
> and in ParaView this mean
>
> o Vector of velocity with "Calculator".: Vel =
> iHat*x_velocity+jHat*y_velocity+kHat*z_velocity
> o Gradients of Vel with "GradientOfUnstructuredDataSet": switch on
> "compute gradient" and name it "Gradients"
> o Calculate lambda with "PythonCalculator".: lambda =
> eigenvalue(strain(Vel)**2+(Gradients - strain(Vel))**2)
> o Caluclate lambda2 with Calculator: lambda2 =
> lambda_Y
>
>
>
> Does anyone see the error why the calculation of lambda2 with ParaView
> does not work?
>
> Remark: i contacted the author of the blog above already - seems he never
> tested his calculation and has no idea what is "wrong".
>
> Stefan
>
>
>
> 
>
>  _/ *Dr. Stefan Melber-Wilkending*
>_/_/
>  _/  _/ Deutsches Zentrum für Luft-
>  _/_/_/_/_/_/_/_/_/_/ und Raumfahrt e.V. (DLR)
>_/_/_/_/
>  _/_/_/_/ German Aerospace Center
>_/_/_/_/_/_/_/_/_/_/  Institute of Aerodynamics
>  _/  _/  _  _   and Flow Technology
>  _/_/   | \ |  |_|   Transport Aircraft Branch
>  _/ |_/ |_ | \
>  Lilienthalplatz 7
>  Fields of activities:  38108 Braunschweig
>  Germany
>  o Numerical Windtunnel Simulation
>  o Aero-Acoustic Windtunnel DesignPhone : +49 531/295-2836
> <(531)%20295-2836>
>  o Numerical Optimization Fax. .: +49 531/295-2914
> <(531)%20295-2914>
>  o Visualization Techniques
>  o High-Lift Aerodynamics   Email : stefan.mel...@dlr.de
>  o Glider-Aerodynamics  Web ..: http://www.dlr.de/AS
>
>
> 
>
>
> ___
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/
> opensource/opensource.html
>
> Please keep messages on-topic and check the ParaView Wiki at:
> http://paraview.org/Wiki/ParaView
>
> Search the list archives at: http://markmail.org/search/?q=ParaView
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/mailman/listinfo/paraview
>
>
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