gradient of total pressure
 

Gents,

I have a question regarding Paraview.
I would like to generate a variable "gradient of total pressure" from cell to cell (or node to node)
Has anyone experience with that?
I think this could be usefull to show, where in the system the biggest pressuredrops are placed.

Thanks for your help
Cheers,
Dito

Hi Dito,

I want to generate the same result. Did you find out how can paraview do that?

Regards,

Subhkirti.

Yes, this was easier as expected :)
There ist a standardfilter called "Gradient of unstructured Dataset" :))
Just mark the Volume -> click on the filter and choose the variable from which you wanna create the gradients. -> In this case Ptot
Works fine.

Cheers
DITO

Gradient of Unstructured Datasets
 

Thanks Dito,

I found the Gradient of Untrstructured Datasets yesterday, but I want not able to get to sensible results due to the following.

On switching to Volume view, my computer gets terribly slow, and does not generate a gradient field, which I saw being generated when it is in the surface mode. If by mark the volume, you mean just selecting the openfoam case, then it is ok. My computer configuration is quite good and a very recent one (2 core, 8GB RAM)

click on the filter and choose the variable from which you wanna create the gradients. Is it different from the pressure field. Mine has only p as the variable. Did you create Ptot from the normalised pressure fields in OpenFoam.

With switching the Geo Representation to volume, Paraview is doing s.th. like volume rendering. This needs a lot of recources.

With volume, I meant the volume in your pipeline browser.
Just mark it and click on the filter. Than select the specific variable.
Paraview will create a new part in your pipeline browser eg. GradientOfUnstructuredDataSet1.
This part, you can use as the source for clips, streamlines and so on.
The clip or streamline you can colour with the new gradient variable.

Reg. Ptot. this is an exported variable out of your solver. I think you forgot to export it.

I have also a question. maybe you have some experience with clipping.
I would like clip a specific section of my model with the planetool. Not the whole domain.
How can I do this? any Idea? And if it is possible, can I move the plane orthogonal to the plane Normal? I only managed to move it along the normal and resize the plane.

Thx
DITO

Paraview clip filter
 

Hi Dito,

Sorry for replying late. I did not understand your question fully, but it looks like you can use a box type in the clip filter to do that.

thanks for reply.
no, this is not what I meant.
when you use the planetool, you clipping the whole volume of your geometry. This is not what I want.
I would like to create a clip not bigger as the planetool is. (implicit - explicit)

Did you manage to get your gradientcoloured Streamline?

DITO

Hello everyone,

First of all, thanks for this thread, it was really helpful.

I just have a question:

I used the Gradient Of Unstructured data filter and chose the U field and i got a new item in the pipeline browser "GradientOfUnstructuredDataSet1".

My question is how do i get the the results i need? how can i export them so i can make the data treatment i need for my work?

Also, is it possible to get results from only a part of the geometry? or the only option is to get results for the whole geometry?

Thanks,

António

Greetings António,

It depends on the exact type of data extraction you're aiming for. But in any case, you can select any item from the "Pipeline Browser", then via menu "File -> Save Data" you can save the data to CSV (aka Comma Separated Values).

Some examples of filters that might come in handy:

• Extract Cells by Region - for getting the actual Cell Data.
• Plot Over Line - for getting interpolated data in specific points.
• Probe Location - better than "Plot Over Line" for getting specific points.
• Resample with Dataset - namely to use another data structure for resampling values.

As for Cell Data vs Point Data, see these posts of mine:

• http://www.cfd-online.com/Forums/ope...tml#post476212 - post #2
• http://www.cfd-online.com/Forums/ope...tml#post446469 - post #12

Best regards,
Bruno

Hi Bruno,

Thank you very much for your detailed answer, it will solve my question.

Best,

António