Negative Volume Elements

windsim · September 20, 2011, 19:22

Hey everyone,

I'm trying to create a mesh in icem then import it to cfx-pre to solve. I've checked the mesh quality for negative volume elements in ICEM, and it tells me that the min element volume is 0.003453 - which I'm assuming means there are no elements with volumes less than that.

However, when I import it over to CFX to solve, the solver tells me that it has found a negative volume element.

Could someone shed some light on this for me please?

Thanks.

brunoc · September 20, 2011, 20:46

Check 'Determinant 2x2x2', or 'Quality'. They tend to deliver negative values for inverted elements. Also, I think there is one function on the 'Edit Mesh > Check Mesh' feature that will search for inverted elements. Try that as well.

windsim · September 20, 2011, 21:15

Thanks for the tip. I've just run mesh diagnostics, but it tells me that there are no issues. Checking the element determinants also yields no negative values. Mesh in CFX is still giving me the same error though.

If it's relevant I'm running the frozen rotor model (but not doing any transient analysis atm).

windsim · September 21, 2011, 00:26

After some work, fixed the neg elements and model is good to go. Thanks

September 20, 2011, 19:22	Negative Volume Elements	#1
windsim New Member Join Date: Dec 2010 Posts: 6 Rep Power: 15	Hey everyone, I'm trying to create a mesh in icem then import it to cfx-pre to solve. I've checked the mesh quality for negative volume elements in ICEM, and it tells me that the min element volume is 0.003453 - which I'm assuming means there are no elements with volumes less than that. However, when I import it over to CFX to solve, the solver tells me that it has found a negative volume element. Could someone shed some light on this for me please? Thanks.

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September 20, 2011, 20:46		#2
brunoc Senior Member Bruno Join Date: Mar 2009 Location: Brazil Posts: 277 Rep Power: 21	Check 'Determinant 2x2x2', or 'Quality'. They tend to deliver negative values for inverted elements. Also, I think there is one function on the 'Edit Mesh > Check Mesh' feature that will search for inverted elements. Try that as well.

September 20, 2011, 21:15		#3
windsim New Member Join Date: Dec 2010 Posts: 6 Rep Power: 15	Thanks for the tip. I've just run mesh diagnostics, but it tells me that there are no issues. Checking the element determinants also yields no negative values. Mesh in CFX is still giving me the same error though. If it's relevant I'm running the frozen rotor model (but not doing any transient analysis atm).

September 21, 2011, 00:26		#4
windsim New Member Join Date: Dec 2010 Posts: 6 Rep Power: 15	After some work, fixed the neg elements and model is good to go. Thanks