Meshing

griff02 · March 18, 2010, 20:15

Hi
I am trying to describe why distorted elements give bad results in FEA and CFD programs for my final year project and cannot find an explanation anywhere. Can anyone help???
Thanks
Oli

jchawner · March 20, 2010, 13:57

Oliver:

Here's a place to start: distortion may reduce numerical accuracy because numerical approximations are no longer centered (or symmetric) about the centroid of the volume element. (from http://www.flow3d.com/cfd101/cfd101_grid.html)

Ahmed · March 20, 2010, 14:25

no matter what discretisation scheme is used, you end up with a matrix that has to be solved.
see what causes the solution of a matrix difficult/inaccurate then trace it back to the distorted mesh elements

julien.decharentenay · March 22, 2010, 08:30

You may be interesting in reading through http://powerlab.fsb.hr/ped/kturbo/Op...jeJasakPhD.pdf

The section on discretisation contains a discussion on orthogonality and others things to pay attention to in the meshing process.

griff02 · March 23, 2010, 08:06

Thanks guys, this is really helpful

March 18, 2010, 20:15	Meshing	#1
griff02 New Member Oliver Griffiths Join Date: Mar 2010 Posts: 2 Rep Power: 0	Hi I am trying to describe why distorted elements give bad results in FEA and CFD programs for my final year project and cannot find an explanation anywhere. Can anyone help??? Thanks Oli

March 20, 2010, 13:57		#2
jchawner Senior Member John Chawner Join Date: Mar 2009 Location: Fort Worth, Texas, USA Posts: 275 Rep Power: 18	Oliver: Here's a place to start: distortion may reduce numerical accuracy because numerical approximations are no longer centered (or symmetric) about the centroid of the volume element. (from http://www.flow3d.com/cfd101/cfd101_grid.html) __________________ John Chawner / jrc@pointwise.com / www.pointwise.com Blog: http://blog.pointwise.com/ on Twitter: @jchawner

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March 20, 2010, 14:25		#3
Ahmed Senior Member Ahmed Join Date: Mar 2009 Location: NY Posts: 251 Rep Power: 18	no matter what discretisation scheme is used, you end up with a matrix that has to be solved. see what causes the solution of a matrix difficult/inaccurate then trace it back to the distorted mesh elements

March 22, 2010, 08:30		#4
julien.decharentenay Senior Member Julien de Charentenay Join Date: Jun 2009 Location: Australia Posts: 231 Rep Power: 18	You may be interesting in reading through http://powerlab.fsb.hr/ped/kturbo/Op...jeJasakPhD.pdf The section on discretisation contains a discussion on orthogonality and others things to pay attention to in the meshing process.

March 23, 2010, 08:06		#5
griff02 New Member Oliver Griffiths Join Date: Mar 2010 Posts: 2 Rep Power: 0	Thanks guys, this is really helpful