# Number of Inflation Layers?

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• Last Post 23 January 2019
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aCVP posted this 21 January 2019

How do you determine the number of inflation layers and overall height needed for accuracy? When I use the "automatic" inflation layer setting, the total height is HUGE (occluding at least 50% of the lumen circumferentially...which seems very incorrect).

For my application: I am assessing the hemodynamic effects of virtually implanting a ventricular assist device within a human heart. Inflation layers will be applied to the vessel and ventricular walls (please see my previous posts for more detail).

Any help would be greatly appreciated - I am having trouble finding good sources for explaining inflation layers and how to determine the inputs.

Thanks!

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kkanade posted this 21 January 2019

in your case suppose your surface mesh size = 1mm.

then please use first prism layer height as say 0.15 to 0.2 mm.

use 5 layers.

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seeta gunti posted this 21 January 2019

Number of Inflation layers depends on many things like flow conditions, objective of the problem, physics you want to model etc. If you know the first cell height and your domain extensions, reynolds number, you can decide on your meshing strategy. Please go through the above vedios and you will understand how to calculate the Y+ and how it is impact the wall functions. Generally, we give 5 - 10 inflation layers to get Y+ 1 to 5 so that we resolve the viscous to buffer layers.

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aCVP posted this 22 January 2019

When I employ the suggested inflation settings, my mesh quality is greatly reduced. Attached are the results.

Also, here are some measures of element quality that I am receiving:

• Avg. Skewness ~0.25
• Avg. Orthogonal Quality ~0.74
• Avg. Element Quality ~0.77

They are not terrible, but they could be better. Is this mesh acceptable? If not... How do I improve my mesh quality?

kkanade posted this 23 January 2019

check min orthogonal quality.

it should be greater than 0.1

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