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-   -   How to find cells whose skewness exceed 0.98 in Fluent? (https://www.cfd-online.com/Forums/fluent/140114-how-find-cells-whose-skewness-exceed-0-98-fluent.html)

swtbkim August 8, 2014 02:50
How to find cells whose skewness exceed 0.98 in Fluent?
 
Hi all!

I made a grid and imported it in fluent and checked case before running calculation

But an error occurred as follows:
Skewness exceeded 0.98 at 3 cells on thread ID = 2.


I want to know the coordinates of these cells in Fluent in order to correct
How should I do?

or, is there another easier way to correct it?


Thanks in advance!

CeesH August 8, 2014 05:37
Hi,

There are a few things you could do. Of course, you could go back to your mesher, check the cells out there, and restructure your mesh in the affected area. This is the advisable solution, because it allows you the most control over what happens to your mesh.

Another option is to fix it in FLUENT itself. You can use adapt/iso-value to select cells that have a skewness or quality value below a certain treshold. Clicking `adapt' will cause fluent to remesh this cells with a finer mesh, which may take away the problem (but it is not guaranteed to do so).

Hope that helps!
Cees

enayath August 8, 2014 10:23
Sangwoo,

I suggest to fix it in mesh section(before import it in Fluent)
In mesh, go to mesh and then click on Statistics and then open the skewness tab and then see where are the worst elements and then try to have a better mesh there

Good Luck,
Hooman

swtbkim August 10, 2014 21:54
Quote:
Originally Posted by CeesH (Post 505005)
Hi,

There are a few things you could do. Of course, you could go back to your mesher, check the cells out there, and restructure your mesh in the affected area. This is the advisable solution, because it allows you the most control over what happens to your mesh.

Another option is to fix it in FLUENT itself. You can use adapt/iso-value to select cells that have a skewness or quality value below a certain treshold. Clicking `adapt' will cause fluent to remesh this cells with a finer mesh, which may take away the problem (but it is not guaranteed to do so).

Hope that helps!
Cees

Thank you for your suggestion!
I will try and leave a feedback.

swtbkim August 10, 2014 21:57
Quote:
Originally Posted by enayath (Post 505061)
Sangwoo,

I suggest to fix it in mesh section(before import it in Fluent)
In mesh, go to mesh and then click on Statistics and then open the skewness tab and then see where are the worst elements and then try to have a better mesh there

Good Luck,
Hooman

You mean in ICEM? I don't know about statistics option.
Unfortunately I use pointwise and I have never been using ICEM...:(

swtbkim August 10, 2014 22:14
Quote:
Originally Posted by CeesH (Post 505005)
Hi,

There are a few things you could do. Of course, you could go back to your mesher, check the cells out there, and restructure your mesh in the affected area. This is the advisable solution, because it allows you the most control over what happens to your mesh.

Another option is to fix it in FLUENT itself. You can use adapt/iso-value to select cells that have a skewness or quality value below a certain treshold. Clicking `adapt' will cause fluent to remesh this cells with a finer mesh, which may take away the problem (but it is not guaranteed to do so).

Hope that helps!
Cees

Iso-value is not activated in Adapt tab..
What can I do?

swtbkim August 11, 2014 02:45
Quote:
Originally Posted by CeesH (Post 505005)
Hi,

There are a few things you could do. Of course, you could go back to your mesher, check the cells out there, and restructure your mesh in the affected area. This is the advisable solution, because it allows you the most control over what happens to your mesh.

Another option is to fix it in FLUENT itself. You can use adapt/iso-value to select cells that have a skewness or quality value below a certain treshold. Clicking `adapt' will cause fluent to remesh this cells with a finer mesh, which may take away the problem (but it is not guaranteed to do so).

Hope that helps!
Cees
Oh never mind. I found it.

But How can I remesh?
Can you explain more detailed procedure?

CeesH August 11, 2014 05:05
I think you need to do 1 iteration before it becomes available.
Then go to adapt -> iso value -> mesh
there you can select the property you want to adapt; so skewness, orthogonal quality, etcetera.
If you click `compute' the minimum and maximum value of the property in the domain are shown. Then you can set the minimum and maximum bounds; the setup will select all cells between these bounds. For example, you can set skewness with min 0.7 and max 1.0 to select all cells with a skewness bigger than 0.7.

Click adapt to remesh them. But again; it would be better to go back to your meshing programme and adapt the mesh there rather than in fluent if that is a possibility for you.

swtbkim August 11, 2014 05:29
Thank you very much!
I will try.

I want to adapt in fluent because doing it in mesher is too difficult...
I needed some automatic function lol
I wish it works

enayath August 11, 2014 20:13
Sangwoo,

No I meant in workbench-->Fluid Flow-->Mesh-->
and the rest of my suggestion.

Hooman

pcbaliwal March 4, 2017 12:56
I also have the same problem.

error occurs:
Skewness exceeded 0.98 at 3 cells on thread ID = 2.

I followed the above answer but didn't solution. I did meshing in fluent.I have no ideas why this error occurs.

Much Thanks in advance.

Balli

swtbkim March 4, 2017 23:09
Quote:
Originally Posted by pcbaliwal (Post 639427)
I also have the same problem.

error occurs:
Skewness exceeded 0.98 at 3 cells on thread ID = 2.

I followed the above answer but didn't solution. I did meshing in fluent.I have no ideas why this error occurs.

Much Thanks in advance.

Balli
Hi.

It is warning that the quality of your mesh is too poor.

Did you try Cees's comment and Joe's?
I have not worked with Fluent Meshing, so I have no idea about it.

I remember that I eventually fixed the problem in meshing tool manually at that time. That is, I found the troublesome cell, and adjusted the node manually until the skewness fell down. It was cumbersome but the only way that I could do.

This is possible in Pointwise, but I'm not sure about Fluent Meshing or ICEM.

enayath March 5, 2017 09:31
Try to re-mesh in Ansys Meshing...
There are ways to decrease the skewness in Fluent as well.


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