[Paraview] ParaView Digest, Vol 64, Issue 8, Message 2

[Berk Geveci]

The integrate variables filter does not compute an average. It
integrates the variables over a surface/volume. To calculate a
(weighted) average, you have to divide by the area/volume. If the
result is still off, let me know - I can investigate if there is a
bug.

-berk

On Wed, Aug 5, 2009 at 4:09 PM, Wei
Wu<Wei.Wu-2 at postgrad.manchester.ac.uk> wrote:
> Dear Tobias,
>
> Many thanks for your help.
>
> Do you think it is necessary to extract the sub-domain, on which I want to
> calculate average value, previous to using the integrate filter?
>
> I am so sorry that I am still confused about the integrate filter. For
> example, I have a result, in which temperatures are in the range 20 ~ 39.5
> degree C. After I apply the integrate filter, I got the temperature value is
> 0.00210551, which is so small. I multiply this value with the cell number,
> 23040, I got 48.5109504, which is beyond the range.
>
> You did mention I have to multiply this averaged value with the calculated
> area value to produce proper values. I feel sorry that I don't truly
> understand this. In my example, the area/volume is very small. They are at
> the level 0.01/0.001. Therefore 0.00210551 times total area/volume cannot
> give a reasonable temperature either. I feel quite confused.
>
> Many thanks in advance for your further help.
>
> Regards, Wei
>
> Quoting Tobias Froebel <tfroebel at gmx.de>:
>
>> Hello Wei,
>>
>> I'm using the Integrate Filter to calculate area- and mass-averaged flow
>> values in planar polydata grids (boundary surfaces) of cfd-models.
>>
>> It's important to convert point-data to cell-data previous to applying
>> the integrate variables filter. After applying this filter you receive
>> area averaged values of every cell-data. Therefore in my case you would
>> have to multiply the averaged value (for example averaged temperature)
>> with the although calculated area value to receive "proper" temperature
>> values.
>>
>> I've never tried to apply the integrate filter on 3D volume data, but I
>> expect volume averaged results, therefore multiplying with the volume
>> value should give you more meaningful values.
>>
>> Tobias
>>
>> --
>> Dipl.-Ing. Tobias Fröbel / CFD
>>
>> Institute for Flight Propulsion / TU Munich
>>
>>> Message: 2
>>> Date: Wed, 5 Aug 2009 12:01:19 +0100
>>> From: "Wei Wu" <wei.wu-2 at postgrad.manchester.ac.uk>
>>> Subject: [Paraview] Average value on specific sub-domains
>>> To: <paraview at paraview.org>
>>> Message-ID:
>>>        <002401ca15bc$0fee9790$2fcbc6b0$@wu-2 at postgrad.manchester.ac.uk>
>>> Content-Type: text/plain; charset="utf-8"
>>>
>>> Dear all,
>>>
>>> I am from Manchester, UK and I am new to CFD calculations. I am using
>>> Code_Saturne(http://code-saturne.blogspot.com) /FVM method to produce data
>>> in EnSight format and then checking it in ParaView. An illustration is
>>> attached. I am working on coolant oil flow and so the picture shows a matrix
>>> of oil flow ducts. This is a 2D model with structured rectangular mesh grid,
>>> but the mesh density is not uniform.
>>>
>>> In order to compare with results from my lumped parameter models, I have
>>> to investigate average values of parameters (the most important one of these
>>> is temperature) on specific sub-domains, as framed out in the picture. I
>>> found a solution
>>> (http://www.paraview.org/pipermail/paraview/2008-April/007882.html) and
>>> tried the filter "integrate variables", but found the result doesn't seem to
>>> be reasonable. I guess I must did something wrong.
>>>
>>> I am quite interested in the extension script by python. Because my model
>>> is constructed by basic geometric elements, and the number of the elements
>>> is growing along with my progress, I am thinking about using python to
>>> obtain average values for all of the sub-domains in a loop. If I can access
>>> information of all the cells in a specific sub-domain (I can compute
>>> coordinate of these domains first), including rectangular cells' sides and
>>> areas as well as the corresponding cell values (temperature, pressure,
>>> velocity etc), I guess it is not difficult to derive average values for all
>>> of the sub-domains.
>>>
>>> I know a little about python and have experience on programming. I looked
>>> up ParaView Wiki, tried some python samples, but unfortunately I still don't
>>> know how to start to implement my idea. Is there a detailed API functions
>>> manual existing? Or could you please give some hints or examples to help?
>>>
>>> Thank you very much for your help about this.
>>>
>>> Best regards,
>>> Wei
>>> -------------- next part --------------
>>> A non-text attachment was scrubbed...
>>> Name: ducts_sample.PNG
>>> Type: image/png
>>> Size: 36866 bytes
>>> Desc: not available
>>> URL:
>>> <http://www.paraview.org/pipermail/paraview/attachments/20090805/70105434/attachment.png
>>>
>> _______________________________________________
>> 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
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.paraview.org/mailman/listinfo/paraview
>>
>
>
> _______________________________________________
> 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
>
> Follow this link to subscribe/unsubscribe:
> http://www.paraview.org/mailman/listinfo/paraview
>