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-   -   how to use the "yPlusRAS"utility (http://www.cfd-online.com/Forums/openfoam/109229-how-use-yplusras-utility.html)

Sunxing November 13, 2012 02:15

how to use the "yPlusRAS"utility
 
Hi foamers

I'm solving a channel folw case with the kEpsilon model.I want the put out the Y+ and U+, but I don't know how to use the YPlusRAS utility. What's more I don't know how to get the U+. So help me please~


Thanks.

Bernhard November 13, 2012 03:15

You can just use the yPlusRAS utility from the command-line, what is not clear about it?

I think generally, the yPlusRAS utility will calculate y*, and not y+.

chegdan November 13, 2012 05:55

In addition to Bernhard's comment, take a look at the thread

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

but make sure to take the time to read through the thread. There are corrections to the provided application and discussion about using of the contributed utility. The link I provided will give you a utility to calculate y+ and u+ and is used for low Reynolds number flows.

Sunxing November 13, 2012 08:33

Just like you said, I have use the yPlusRAS utility from the command-line. But I got an error ——
cannot open file

file: /home/sun/OpenFOAM/sun-2.1.1/1112/constant/transportProperties at line 0.

From function regIOobject::readStream()
in file db/regIOobject/regIOobjectRead.C at line 87.

FOAM exiting

While there is no the transportProperties file in my case actually because I use the rhoPimpleFoam solver for my case and it maybe a bad choice for me to choose this solver.

At first, I want to apply a solver from the incompressible directory because my case is a simple channel flow (1, low Re number; 2, the temperature of the inlet air is 300k,the temperature of the wall is 310k; 3, epsilon=46,k=0.7) While I find that all the cases in the incompressible directory have no dealing with the temperature and I don't know how to add it in the solver, so I chose the rhoPimpleFoam solver for my case and I don't know if it is a right one.

In your opinion, what solver should I choose?
What's more, what is y* ?

Sunxing November 13, 2012 08:36

Quote:

Originally Posted by Bernhard (Post 391765)
You can just use the yPlusRAS utility from the command-line, what is not clear about it?

I think generally, the yPlusRAS utility will calculate y*, and not y+.


First, thanks for your reply.
Just like you said, I have use the yPlusRAS utility from the command-line. But I got an error
cannot open file

file: /home/sun/OpenFOAM/sun-2.1.1/1112/constant/transportProperties at line 0.

From function regIOobject::readStream()
in file db/regIOobject/regIOobjectRead.C at line 87.

FOAM exiting

While there is no the transportProperties file in my case actually because I use the rhoPimpleFoam solver for my case and it maybe a bad choice for me to choose this solver.

At first, I want to apply a solver from the incompressible directory because my case is a simple channel flow (1, low Re number; 2, the temperature of the inlet air is 300k,the temperature of the wall is 310k; 3, epsilon=46,k=0.7) While I find that all the cases in the incompressible directory have no dealing with the temperature and I don't know how to add it in the solver, so I chose the rhoPimpleFoam solver for my case and I don't know if it is a right one.

In your opinion, what solver should I choose?
What's more, what is y* ?

Sunxing November 13, 2012 08:39

Quote:

Originally Posted by chegdan (Post 391799)
In addition to Bernhard's comment, take a look at the thread

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

but make sure to take the time to read through the thread. There are corrections to the provided application and discussion about using of the contributed utility. The link I provided will give you a utility to calculate y+ and u+ and is used for low Reynolds number flows.


Dear Dan

Thanks for your reply. It's very helpful for me. Thanks again!:)

doubtsincfd November 13, 2012 17:34

since you are using a compressible solver, use yplusRAS -compressible

Sunxing November 13, 2012 22:00

Quote:

Originally Posted by doubtsincfd (Post 391933)
since you are using a compressible solver, use yplusRAS -compressible

Hello Omkar,

Thanks for your reply. I will have a try.

Best
Sunxing

Sunxing November 20, 2012 10:52

Quote:

Originally Posted by Bernhard (Post 391765)
You can just use the yPlusRAS utility from the command-line, what is not clear about it?

I think generally, the yPlusRAS utility will calculate y*, and not y+.


Hi,

Can you give me a exact explaination of y*? I don't know what does it stand for.

thanks!

chegdan November 20, 2012 10:58

Quote:

Originally Posted by Sunxing (Post 393216)
Hi,

Can you give me a exact explaination of y*? I don't know what does it stand for.

thanks!

The definition
http://www.cfd-online.com/Forums/ope...lus-ystar.html

Sunxing November 20, 2012 11:01

Quote:

Originally Posted by chegdan (Post 393217)

Hi Dan

Thank you very much

Sunxing


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