[ANSYS Meshing] STRANGE negative quality for elements

mohammad · December 22, 2011, 03:12

Dear all, I am trying to mesh an airfoil ( 2D ) with a split with ICEM 11.
I have created the Parasolid file is Solidworks 2010 and imported the file to ICEM.
every thing seems to be alright , and just when i create the hexa mesh, I can see at one line related to split edge at the suction surface the quality is negative.
This is because the ICEM creates and considers some very small imaginary small surfaces that do not exist in the geometry( in reality) and you can not see them physically, but they exist in mathematical considerations for the geometry.
this imaginary non existing areas ( and curves) although are not being associated with any edges, but absorb some edges to themselves ( by the software) and make some elements with negative qualities.
A i told you , investigation of the geometry shows no sign of such surfaces and curves, but observation of the elements shows those badly twisted elements with negative quality.
I want to ask has anyone faced this problem before and how to solve it.

thanks

PSYMN · December 23, 2011, 18:03

Pop in a picture and I am sure we can sort it out...

mohammad · December 24, 2011, 01:59

Hi everybody,
I have solved this problem by creating the geometry of my model in Catia V17 and subsequently importing IGS file into the ICEM V13.

Because I have deleted all my wrong files, i do not have any picture of those files but this problem happened for me several times when at the edges when suction surface( or pressure surface ) is cut with a split sharply.

December 22, 2011, 03:12	STRANGE negative quality for elements	#1
mohammad Senior Member mohammad Join Date: Dec 2010 Location: UK Posts: 245 Rep Power: 16	Dear all, I am trying to mesh an airfoil ( 2D ) with a split with ICEM 11. I have created the Parasolid file is Solidworks 2010 and imported the file to ICEM. every thing seems to be alright , and just when i create the hexa mesh, I can see at one line related to split edge at the suction surface the quality is negative. This is because the ICEM creates and considers some very small imaginary small surfaces that do not exist in the geometry( in reality) and you can not see them physically, but they exist in mathematical considerations for the geometry. this imaginary non existing areas ( and curves) although are not being associated with any edges, but absorb some edges to themselves ( by the software) and make some elements with negative qualities. A i told you , investigation of the geometry shows no sign of such surfaces and curves, but observation of the elements shows those badly twisted elements with negative quality. I want to ask has anyone faced this problem before and how to solve it. thanks

December 23, 2011, 18:03		#2
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Pop in a picture and I am sure we can sort it out... __________________ ----------------------------------------- Please help guide development at ANSYS by filling in these surveys Public ANSYS ICEM CFD Users Survey This second one is more general (Gambit, TGrid and ANSYS Meshing users welcome)... CFD Online Users Survey

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December 24, 2011, 01:59		#3
mohammad Senior Member mohammad Join Date: Dec 2010 Location: UK Posts: 245 Rep Power: 16	Hi everybody, I have solved this problem by creating the geometry of my model in Catia V17 and subsequently importing IGS file into the ICEM V13. Because I have deleted all my wrong files, i do not have any picture of those files but this problem happened for me several times when at the edges when suction surface( or pressure surface ) is cut with a split sharply.