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[ICEM] Aspect Ratio Problem

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Old   March 11, 2018, 18:26
Default Aspect Ratio Problem
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I try to generate a mesh in ICEM CFD for naca0012. However, Aspect Ratio be a huge problem for the following data.
Dynamic Viscosity: 1.13E-03 (for sea water)
Velocity: 6.625 m/s
Density: 1025 kg/m3
Chord Length: 1 m
Y+ desired: 1
Since the k-omega SST turbulence model is selected, y+ desired should be smaller than 5.
Finally, pointwise y+ calculator give me that value for the wall spacing: 8.9E-06
This value, which is so small be a problem for the aspect ratio.
As I know, Aspect ratio should be smaller than 100. But in this condition aspect ratio is defined as bigger than 10000.
How can I overcome this problem?
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Old   March 12, 2018, 09:11
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Quote:
Originally Posted by thebuaa View Post
I try to generate a mesh in ICEM CFD for naca0012. However, Aspect Ratio be a huge problem for the following data.
Dynamic Viscosity: 1.13E-03 (for sea water)
Velocity: 6.625 m/s
Density: 1025 kg/m3
Chord Length: 1 m
Y+ desired: 1
Since the k-omega SST turbulence model is selected, y+ desired should be smaller than 5.
Finally, pointwise y+ calculator give me that value for the wall spacing: 8.9E-06
This value, which is so small be a problem for the aspect ratio.
As I know, Aspect ratio should be smaller than 100. But in this condition aspect ratio is defined as bigger than 10000.
How can I overcome this problem?
Increase the number of cells streamwise on airfoil. By the way modern CFD solvers can solve really high aspect ratios (in thousands) unless it is ridiculously high this is not a problem in my opinion.
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Old   March 14, 2018, 10:59
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Quote:
Originally Posted by thebuaa View Post
I try to generate a mesh in ICEM CFD for naca0012. However, Aspect Ratio be a huge problem for the following data.
Dynamic Viscosity: 1.13E-03 (for sea water)
Velocity: 6.625 m/s
Density: 1025 kg/m3
Chord Length: 1 m
Y+ desired: 1
Since the k-omega SST turbulence model is selected, y+ desired should be smaller than 5.
Finally, pointwise y+ calculator give me that value for the wall spacing: 8.9E-06
This value, which is so small be a problem for the aspect ratio.
As I know, Aspect ratio should be smaller than 100. But in this condition aspect ratio is defined as bigger than 10000.
How can I overcome this problem?
1. Increase no of nodes on airfoil surface.

2. Moreover try Y+ ~ 10 would you same results as Y+~-

Watch this video for same : https://www.youtube.com/watch?v=3VuZiDIl704
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Old   March 14, 2018, 15:07
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Originally Posted by shereez234 View Post
Increase the number of cells streamwise on airfoil. By the way modern CFD solvers can solve really high aspect ratios (in thousands) unless it is ridiculously high this is not a problem in my opinion.
Thank you so much.
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Old   March 14, 2018, 15:10
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Originally Posted by Far View Post
1. Increase no of nodes on airfoil surface.

2. Moreover try Y+ ~ 10 would you same results as Y+~-

Watch this video for same : https://www.youtube.com/watch?v=3VuZiDIl704
Dear Sir

I have watched your video before. But you don't check the aspect ratio in your video. And in my opinion, aspect ratio shoud not lower than 1000 for your mesh.
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