please help me understand the output of wallShearStress

New-to-CFD · May 2, 2020, 14:55

Hello,

I'm very new to openfoam and developing some post-processing / sampling functionality for my cases.

Things are working out well, but I was wondering if you guys could help me understand the output of the wallShearStress function

currently, I am running it like:

Code:

postProcess -func "wallShearStress"

and it outputs something that looks like this:

Screenshot from 2020-05-02 13-50-32.png

granted the results aren't very interesting, I'm just trying to get the functionality down for when I need it.

Can someone help me understand what the actually output is, and units? Assuming Pa?

I tried to look in the documentation/api docs but I'm getting a 404 error on some webpages and can't seem to find the output description anywhere?

What exactly are these numbers

?

Also, if anyone can tell me how to only calculate wallShearStress on a specific patch, that'd be great...currently when I do something like:

Code:

postProcess -func "wallShearStress(name=bottom)"

it just says:

Code:

wallShearStress wallShearStress:
    processing all wall patches

at some point I will want to only sample a specific patch...how can I do this??

OFv1912

Thanks all.

Yann · May 4, 2020, 06:37

Hi !

Have a look at the documentation of the wallShearStress function : https://www.openfoam.com/documentati...earStress.html

Cheers,
Yann

May 2, 2020, 14:55	please help me understand the output of wallShearStress	#1
New-to-CFD New Member MASc Student Join Date: Sep 2016 Posts: 25 Rep Power: 11	Hello, I'm very new to openfoam and developing some post-processing / sampling functionality for my cases. Things are working out well, but I was wondering if you guys could help me understand the output of the wallShearStress function currently, I am running it like: Code: postProcess -func "wallShearStress" and it outputs something that looks like this: Screenshot from 2020-05-02 13-50-32.png granted the results aren't very interesting, I'm just trying to get the functionality down for when I need it. Can someone help me understand what the actually output is, and units? Assuming Pa? I tried to look in the documentation/api docs but I'm getting a 404 error on some webpages and can't seem to find the output description anywhere? What exactly are these numbers ? Also, if anyone can tell me how to only calculate wallShearStress on a specific patch, that'd be great...currently when I do something like: Code: postProcess -func "wallShearStress(name=bottom)" it just says: Code: wallShearStress wallShearStress: processing all wall patches at some point I will want to only sample a specific patch...how can I do this?? OFv1912 Thanks all.

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May 4, 2020, 06:37		#2
Yann Senior Member Yann Join Date: Apr 2012 Location: France Posts: 1,360 Rep Power: 33	Hi ! Have a look at the documentation of the wallShearStress function : https://www.openfoam.com/documentati...earStress.html Cheers, Yann