TAGGED: ansysfluent, cfd-fluent
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October 16, 2024 at 2:18 amz5456415Subscriber
Hi,
I have a pitching airfoil (chord = 0.15m) simulation (pitches after a certain time using UDF). When I the simulation with Re = 2e6 (v = 197 m/s), at the beginning itself I am getting this message "turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 640565 cells". Also, the values for cl, cd, cm, etc are unrealistic huge values.
What could be the reason for this and how can I solve this? The model works under small velocity (v=10m/s).
Can anyone please help with this?
y+ value is below 1 and CFL set to 0.1.
Regards,
Muhammed Sadique
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October 16, 2024 at 8:57 amRobForum Moderator
You may need to check inlet boundary conditions. Do the number of cells hitting the limiter reduce with iterations?
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November 4, 2024 at 2:32 amz5456415Subscriber
Hi Rob,
Thank you very much for your reply.
I did not check by changing the number of iterations. However, I changed the case with low velocity (10 or 30 m/s) and the simulation gives reliable results.
I do have another question about meshing. Please advise me if I have to post it separately in another thread.
When going for a fine mesh, or increasing the domain size, I am getting the following error,
“The specified defeaturing tolerance was found to be larger than a specified size. The elements on one or more edges may be defeatured out.”
Could you please tell me how I can resolve this? Though it shows the above error, a small portion of the domain is getting meshed properly.
Please find the image below, the geometry, where the domain with airfoil is getting meshed properly, where I thought the meshing will be complex and difficult.
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November 4, 2024 at 9:39 amRobForum Moderator
I'd avoid odd shapes around a wing as you may trigger unwanted mesh resolution due to the curvature. Check defeaturing relative to smallest cell size. The check is to warn if you're trying to mesh to a greater resolution than you are simplifying the geometry to.
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