[nikhil07071990]

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]

This sounds like a problem I just had: Unwanted "Primitive 2D" surfaces shown in CFx-PRE


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

[nikhil07071990]

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]

Originally Posted by nikhil07071990

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]

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]

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]

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]

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]

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]

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]

Originally Posted by nikhil07071990

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]

Originally Posted by nikhil07071990

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]

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]

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

[themrdjj]

Originally Posted by nikhil07071990

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

I'll send you a PM.