[ANSYS Meshing] Difference between average skewness and maximum skewness

ParasuRam · February 14, 2018, 10:32

Hello, I am trying to simulate a 2D, unsymmetrical airfoil and i am using unstructured mesh. The following are the skewness values of my mesh:

1. Min Skewness: 3.015* e-07
2. Max Skewness: 0.94216
3. Average Skewness: 6.54*e-02
4. Standard Deviation: 9.4*e-02

The standard deviation and average skewness are very less while maximum skewness is very high.

What should be the deciding parameter before proceeding to solve? Average skewness? or Maximum Skewness? Does this depend on things like physics of the flow, location of this max skewed element, etc ? If so, how?

Thank you

shereez234 · February 14, 2018, 13:44

Maximum Skeweness is what you should be keeping an eye out for. The solvers in ANSYS(fluent,cfx) is very capable of handling bad meshes.

However, i must say that a bad skew element will effect your solution and convergence (stability) (thus the physics of the solution). So its good to improve the skewness and (orthogonality, aspect ratio and minimum angle) as much as you can before you take the mesh to solver.

ParasuRam · February 15, 2018, 04:47

Thank you sir for the reply

Is there a way in Ansys Meshing, or Fluent, to reduce the skewness of a few selective elements?

shereez234 · February 15, 2018, 05:34

Quote:

Originally Posted by ParasuRam

Thank you sir for the reply

Is there a way in Ansys Meshing, or Fluent, to reduce the skewness of a few selective elements?

ofcourse. if you show the problematic area with pictures a lot of people on this forum will help

siw · February 15, 2018, 06:22

Unlike in ICEM, smoothing in ANSYS Meshing is applied to the entire mesh and up until R19 it was only defined by choosing one option from three in a drop down list. If you want much greater control in making and editing a mesh move to ICEM.

February 14, 2018, 10:32	Difference between average skewness and maximum skewness	#1
ParasuRam New Member Ramana Join Date: Sep 2017 Posts: 2 Rep Power: 0	Hello, I am trying to simulate a 2D, unsymmetrical airfoil and i am using unstructured mesh. The following are the skewness values of my mesh: 1. Min Skewness: 3.015* e-07 2. Max Skewness: 0.94216 3. Average Skewness: 6.54e-02 4. Standard Deviation: 9.4e-02 The standard deviation and average skewness are very less while maximum skewness is very high. What should be the deciding parameter before proceeding to solve? Average skewness? or Maximum Skewness? Does this depend on things like physics of the flow, location of this max skewed element, etc ? If so, how? Thank you

February 15, 2018, 04:47	Way to reduce skewness	#3
ParasuRam New Member Ramana Join Date: Sep 2017 Posts: 2 Rep Power: 0	Thank you sir for the reply Is there a way in Ansys Meshing, or Fluent, to reduce the skewness of a few selective elements?

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February 14, 2018, 13:44		#2
shereez234 Senior Member MS Join Date: Jan 2014 Location: England Posts: 343 Blog Entries: 1 Rep Power: 12	Maximum Skeweness is what you should be keeping an eye out for. The solvers in ANSYS(fluent,cfx) is very capable of handling bad meshes. However, i must say that a bad skew element will effect your solution and convergence (stability) (thus the physics of the solution). So its good to improve the skewness and (orthogonality, aspect ratio and minimum angle) as much as you can before you take the mesh to solver.

February 15, 2018, 06:22		#5
siw Senior Member Stuart Join Date: Jul 2009 Location: Portsmouth, England Posts: 712 Rep Power: 24	Unlike in ICEM, smoothing in ANSYS Meshing is applied to the entire mesh and up until R19 it was only defined by choosing one option from three in a drop down list. If you want much greater control in making and editing a mesh move to ICEM.