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-   -   Using vorticity utility and meaning of curl (U) (http://www.cfd-online.com/Forums/openfoam-post-processing/119492-using-vorticity-utility-meaning-curl-u.html)

aligoger June 18, 2013 11:13

Using vorticity utility and meaning of curl (U)
 
Dear Foamers,

I am planing to use vorticity as a post processing utility. When I hit the vorticity command in terminal the error comes up:

Time = 1500
Reading U
Calculating vorticity
--> FOAM Warning :
--> FOAM FATAL IO ERROR:
keyword curl(U) is undefined in dictionary "/home/ali/run/2/system/fvSchemes::gradSchemes"


1. Is there any body explain me what the curl(U) is?
2. Is there any suggestion for the most suitable gradSchemes for curl(U) in fvSchemes?

I really appreciate for any help.

chegdan June 19, 2013 14:58

1. Curl(U) is the cross product of the vector differential operator and the velocity vector explained here

2. for grad schemes, I like least squares defined like
Code:

grad(U) leastSquares;
found from here

Enjoy

gaza September 27, 2013 15:34

hi foamers
I have the same problem as aligoger. Did anybody solve this problem?

best

wyldckat September 27, 2013 21:01

Greetings to all!

@gaza:
Quote:

Originally Posted by gaza (Post 453925)
I have the same problem as aligoger. Did anybody solve this problem?

What Daniel meant is that you should edit the file "system/fvSchemes" and find the block that starts with "gradSchemes", e.g.:
Code:

gradSchemes
{
    default        Gauss linear;
    grad(p)        Gauss linear;
}

And add the entry for "curl(U)":
Code:

gradSchemes
{
    default        Gauss linear;
    grad(p)        Gauss linear;
    curl(U) leastSquares;
}

Best regards,
Bruno

gaza September 28, 2013 01:42

Hi Bruno
In fvScheme I had set up
gradSchemes
{
default none;
grad(p) Gauss linear;
grad(U) Gauss linear;
}

Today when I changed this to
gradSchemes
{
default Gauss linear;
// grad(p) Gauss linear;
// grad(U) Gauss linear;
}
it works. I don't know why and this is strange for me.
I haven't had to set up curl(U).
Very thank you for your ultra fast replay and help.

best
Przemek

gaza September 28, 2013 01:50

It seems that settings: default none
in gradSchemes cannot be set up if I want to calculate vorticity
with vorticity utility.

best
Przemek


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