Post processing tools

A subforum specific to the development of the OpenFoam-based workbenches ( Cfd https://github.com/qingfengxia/Cfd and CfdOF https://github.com/jaheyns/CfdOF )

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julieng
Posts: 38
Joined: Sun Nov 25, 2018 8:57 pm

Post processing tools

Postby julieng » Sun Dec 16, 2018 8:42 am

Hello,

Is there any macros or patches to calculate for example the mass flow rate ?
How do you proceed ?

Sorry but i have very few experience with openfoam

Best regards
thschrader
Posts: 1383
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: Post processing tools

Postby thschrader » Sun Dec 16, 2018 11:31 am

In paraview, use filters "slice" and "integrate variables".
In this case, Ux represents the volume-flow at the slice.
Multiplied by the fluid density you get the mass-flow through the slice.
But if you have an incompressible fluid, the mass flow at every slice at the channel
must be the same, so you can calculate the mass flow from your inlet parameters.
volume_flow.JPG
volume_flow.JPG (157 KiB) Viewed 392 times
julieng
Posts: 38
Joined: Sun Nov 25, 2018 8:57 pm

Re: Post processing tools

Postby julieng » Sun Dec 16, 2018 1:44 pm

Thank you thschrader,

Ok I have test it, is a simple and good solution for incompressible flow.
I try to compute a compressible flow case but I have some error.

Is the volumic mass data available in Paraview for compressible mass flows calculation?

Image

Best regards

Julien
thschrader
Posts: 1383
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: Post processing tools

Postby thschrader » Sun Dec 16, 2018 6:16 pm

julieng wrote:
Sun Dec 16, 2018 1:44 pm
I try to compute a compressible flow case but I have some error.
Can you post your FC-file?
It is hard to guess a solution...
julieng
Posts: 38
Joined: Sun Nov 25, 2018 8:57 pm

Re: Post processing tools

Postby julieng » Sun Dec 16, 2018 9:43 pm

I have the following error

Image

My case is joined

Best regards

Julien
Attachments
test9.FCStd
compressible case
(27.82 KiB) Downloaded 10 times
thschrader
Posts: 1383
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: Post processing tools

Postby thschrader » Sun Dec 16, 2018 11:57 pm

julieng wrote:
Sun Dec 16, 2018 9:43 pm
My case is joined
You are using the His solver for pipe flow with 0,5 m/s inlet speed.
Hisa was developed for external high speed aerodynamics.
http://hisa.gitlab.io/

However, at inlet/outlet use the far-field boundary. Here are some examples:
falcon9.FCStd
(51.47 KiB) Downloaded 9 times
bullet.FCStd
(17.81 KiB) Downloaded 10 times
https://forum.freecadweb.org/viewtopic. ... 1&start=10
Bedtime...
julieng
Posts: 38
Joined: Sun Nov 25, 2018 8:57 pm

Re: Post processing tools

Postby julieng » Fri Dec 21, 2018 5:26 am

Hello

Do you know how to plot the drag and lift forces on function of time with paraview?

I do the same steps extract surface, generate normals, calculate pressure x normal x Rho.

If i try integrate variable and plot other time i have nothing in my graph.

Best regards
thschrader
Posts: 1383
Joined: Sat May 20, 2017 12:06 pm
Location: Germany

Re: Post processing tools

Postby thschrader » Fri Dec 21, 2018 9:01 am

julieng wrote:
Fri Dec 21, 2018 5:26 am
Hello
Do you know how to plot the drag and lift forces on function of time with paraview?
I do the same steps extract surface, generate normals, calculate pressure x normal x Rho.
If i try integrate variable and plot other time i have nothing in my graph.
Best regards
Not from scratch. I will have a look at it.
When generating surface normals, dont forget to enable "compute cell normals".
After integrating the variables, switch from point data to cell data in List.
Thomas
julieng
Posts: 38
Joined: Sun Nov 25, 2018 8:57 pm

Re: Post processing tools

Postby julieng » Fri Dec 21, 2018 11:28 am

Hello thschrader,

I have done "compute cell normals" and also choose cell data in the integration list.

Best regards