Cell areas in a patch
 

Dear all,

I have a trapezoidal pipe network that I have completed a simulation for. I now need to find the area-weighted average of the wall shear stress of which I need to know the cell area.

Previously all my simulation have been with rectangular cross sections so I have been able to find out the cell area with ease by doing it manually.

I have come across this post about finding the cell areas:
http://www.cfd-online.com/Forums/ope...rea-patch.html

and that subsequently refers you to this post:
http://www.cfd-online.com/Forums/ope...tml#post297002

They suggest various lines of code to be implemented. But since I am a pretty new user of openFoam and linux in general, I am not too sure of how and where they are implementing this code? Does anyone have any suggestions?

Or an alternative technique?

The answer

http://www.cfd-online.com/Forums/ope...nt-planes.html

quick regex solution
 

TLDR:use this regex code, only tested in openfoam 4! ;)
Full Description:
By using the postProcess function utility we can check the value of a field such as U,p,k,nut, T over a whole patch. To be able to have the integrated value the computer must have an area. Luckily that area gets printed when we perform a funciton such as integrate velocity over a face. So then you can just use regex string to manipulate the return from openfoam. Notes that I am not a regex star, so i did an exact string which requires that there is a line with 'total area' followed by 3 spaces and then an equals sign. If someone else has a better solution then pls supply :D



1. GO TO THE CASE DIRECTORY

1. change directory to case you want to analyze
2. punch this in
   (must replace somePatchName, someFieldName
   
   
   Code:

   ---

   postProcess -func 'patchIntegrate(name=somePatchName,someFiledName)' | grep -Po "((?<=total area  =).*([0-9])*)"

   ---

Here is an applied example in which the "inlet" patch is the one i want to find the area of and I use the U field to get it's area printed. This works because my simulation calculates the velocity. Whether the velocity is a set value or is varied by the solver is irrelevant.

that will print the value to the terminal, in reality this will work with most programming languages bc they all support regex.







While the openfoam naitive compilation is a great solution. Here is a a