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-   -   [ICEM] NEED HELP!! Uncovered faces (https://www.cfd-online.com/Forums/ansys-meshing/211035-need-help-uncovered-faces.html)

nikhil07071990 November 10, 2018 05:02

NEED HELP!! Uncovered faces
 
Hi everyone! I am having trouble in getting rid of uncovered faces in between the two blocks(please see the link for the image below).

The link for the image is :

https://drive.google.com/open?id=126...56BRc8YhWSVQxG

themrdjj November 11, 2018 12:34

This sounds like a problem I just had: https://www.cfd-online.com/Forums/cf...n-cfx-pre.html


In my case I merged the "double" nodes of the mesh at the interface between these "uncovered volumes".

nikhil07071990 November 11, 2018 17:28

Thanks for the reply! We merged the vertices earlier and that's how we got the uncovered faces. I read your thread and I was wondering how did you delete the mesh surfaces

themrdjj November 11, 2018 20:14

Quote:

Originally Posted by nikhil07071990 (Post 714890)
Thanks for the reply! We merged the vertices earlier and that's how we got the uncovered faces. I read your thread and I was wondering how did you delete the mesh surfaces


Edit Mesh -> Delete elements


If you hide the mesh volumes then you should be only able to select mesh surfaces.


You're also working on AE4202, aren't you? It's 2:15 right now and there's no end in sight...

nikhil07071990 November 12, 2018 03:36

Haha ya man. And now, we are struggling with reducing the y+ value. I wish you good luck .

I'll try out what you just wrote

themrdjj November 12, 2018 07:33

I managed to run the simulation on my y+<1 mesh this morning at 4:00, so I might be able to help if you have some minor issue. You might get an error message about Hexahedral elements being degenerated, in that case I can definitely help.

nikhil07071990 November 12, 2018 07:56

Nice. Good for you! Well, I don't have that error but I just can't seem to bring y+ below 2.5. I use this -- https://www.computationalfluiddynami...t-cell-height/ -- to calculate the max height of the cell.

themrdjj November 12, 2018 07:59

Why not? If you use all the correct options there you should get a cell height of something to the power of -6. Is it just showing NaN for you?

nikhil07071990 November 12, 2018 08:03

I am using a value of 9.23e-7. What did you use?
I put velocity as 250.047 m/s
length - 1m
Density - 1.21 kg/m3
Viscosity - 18.03e-6

nikhil07071990 November 12, 2018 08:31

I just realised where I am going wrong but I dont know how to fix it. Y+ plus is less than one everywhere but at the rear of the airfoil. It seems as if the rear part of the airfoil is in another block. Any idea how to fix that?

themrdjj November 12, 2018 08:49

Quote:

Originally Posted by nikhil07071990 (Post 714954)
I am using a value of 9.23e-7. What did you use?
I put velocity as 250.047 m/s
length - 1m
Density - 1.21 kg/m3
Viscosity - 18.03e-6


That density is incorrect. Apply the ideal gas law to the given boundary conditions.

themrdjj November 12, 2018 08:51

Quote:

Originally Posted by nikhil07071990 (Post 714957)
I just realised where I am going wrong but I dont know how to fix it. Y+ plus is less than one everywhere but at the rear of the airfoil. It seems as if the rear part of the airfoil is in another block. Any idea how to fix that?


I set the first cell height at the wall to the required value (for y+=1) everywhere on the airfoil. Shouldn't that mean that I have a y+ of 1 everywhere? Or do I need to take into account the "local" density, viscosity and velocity? I didn't think about this before tbh.

nikhil07071990 November 12, 2018 09:58

Thanks for your help! We solved the problem. I think you have to consider the local variables/parameters. But as long as you get y+ less than i guess you dont need to look into it

nikhil07071990 November 12, 2018 12:44

Which model did you choose for anisotropic turbulence and which advection scheme?

themrdjj November 12, 2018 14:50

Quote:

Originally Posted by nikhil07071990 (Post 714987)
Which model did you choose for anisotropic turbulence and which advection scheme?


I'll send you a PM.


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