[ANSYS Meshing] inflation for a 1 mm pipe

katwre · November 21, 2022, 23:53

Hello,

I am currently designing a tube of 1 mm, i have implemented inflation for the model because I will be working on turbulent flow. I am currently looking for a way to verify the mesh. In larger pipes I have seen that you can use y+ values to adjust the mesh. The best value i have gotten so far is y+= 0.4 for an inlet velocity of 18.26 m/s and L = 5D.
I have read that y+ should be between 30 and 300 for turbulent models but in my case a y+ = 30 is impossible to obtain since it will lead to a first element height larder than my geometry. So how can I ensure that my mesh is robust? I will be using k-ω sst for this simulation.

Thank you in advance

Gert-Jan · November 23, 2022, 09:47

kw SST performs well between Yplus 0.1 and 300.
but if the solution is correct, depends on our mesh quality, size, skewness, inlet conditions, etc.

so better plot a few lines to see how velocity, pressure, tke, omega, TED etc develop and see if it converges. Or not.
What is your Reynolds?

zacko · November 24, 2022, 11:39

You are probably working with air (my quick check with your given boundary conditions) ? If the first layer height is too great, decrease your desired y+ value to around 1. This will resolve your boundary layer and decrease your first layer height enough.

November 21, 2022, 23:53	inflation for a 1 mm pipe	#1
katwre New Member Join Date: Nov 2022 Posts: 4 Rep Power: 3	Hello, I am currently designing a tube of 1 mm, i have implemented inflation for the model because I will be working on turbulent flow. I am currently looking for a way to verify the mesh. In larger pipes I have seen that you can use y+ values to adjust the mesh. The best value i have gotten so far is y+= 0.4 for an inlet velocity of 18.26 m/s and L = 5D. I have read that y+ should be between 30 and 300 for turbulent models but in my case a y+ = 30 is impossible to obtain since it will lead to a first element height larder than my geometry. So how can I ensure that my mesh is robust? I will be using k-ω sst for this simulation. Thank you in advance

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November 23, 2022, 09:47		#2
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	kw SST performs well between Yplus 0.1 and 300. but if the solution is correct, depends on our mesh quality, size, skewness, inlet conditions, etc. so better plot a few lines to see how velocity, pressure, tke, omega, TED etc develop and see if it converges. Or not. What is your Reynolds?

November 24, 2022, 11:39		#3
zacko Senior Member Daniel Join Date: Feb 2017 Location: Germany Posts: 147 Rep Power: 9	You are probably working with air (my quick check with your given boundary conditions) ? If the first layer height is too great, decrease your desired y+ value to around 1. This will resolve your boundary layer and decrease your first layer height enough.