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-   -   [ICEM] What is the reason for this negative determinant? (http://www.cfd-online.com/Forums/ansys-meshing/112300-what-reason-negative-determinant.html)

kiddmax January 25, 2013 12:05

What is the reason for this negative determinant?
 
1 Attachment(s)
Hello,guys.

Now I want to simulate the flow over wind turbine rotor, but when I am doing the mesh, there is a problem that says negative determinant when I check the mesh. you can see the bad cells(green) in the picture. so I want to know what is the reason for negative determinant and how to improve the bad cells? Thank you in advance.

Regards
Ye

diamondx January 25, 2013 12:40

sometimes a simple update of the blocking can solve the problem.
best way to track those element is by using the scan edge or cut plane...

kiddmax January 25, 2013 13:28

Hi, M.Ali

Thank you for your reply.
I can track(see)the bad cell, what I don't know is how to improve it? The green cells that have negative determinant looks quite triangle, right? but after the sharp trailing edge, I have get two blocks, is this the right method to deal with sharp edge?

regards,
Ye

Catthan April 18, 2013 09:59

kiddmax have you found a way to sort this?

I'm having the exact same problem with a sharp edge.

The geometry and even the histogram look frighteningly similar too,,

Let me know.

Best,

kiddmax April 18, 2013 10:13

Hi, Catthan

What about your blade? is it 3D or 2D?

I advice you to use C grid for the sharp trailing edge. This is a tutorial on youtube.
http://www.youtube.com/watch?v=mgjRT4WY_iA

and make sure to use a block for "boundary layer", that will be much better.
just like this

kiddmax April 18, 2013 10:15

1 Attachment(s)
this is the picture

diamondx April 18, 2013 10:59

scan plane and cut plane are the best tools to look for thoe negative elements...


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