[Nek5000-users] Vanishing Jacobian error description

[nek5000-users at lists.mcs.anl.gov]

Hi Paul, 



Here is the rea, usr, & SIZE file I am using.  I ran it again without the curved side information and it worked, so I think the problem is somewhere in the curved side section of the rea. 



The geometry is a square base lofted into a circle in the +z direction.  The mesh was generated in gambit. I've developed a matlab code that will take a mesh created in gambit and generate the required REA formatting. I have created some basic shapes to test the matlab portion and the curved side portion, and it worked in most cases (not this one yet). I'm not sure what is going on with the curved side data in this case however. 



Thanks for looking at this, 

Michael 


----- Original Message ----- 
From: nek5000-users at lists.mcs.anl.gov 
To: "Nekton User List" <nek5000-users at lists.mcs.anl.gov> 
Sent: Tuesday, April 20, 2010 3:36:44 PM GMT -06:00 US/Canada Central 
Subject: Re: [Nek5000-users] Vanishing Jacobian error description 



Michael, 

The code is trying to check to ensure that the mesh is 
valid.  Sometimes, however, there are other causes for 
the problem. 

Can you send a gzip'd rea/usr file, and I can take a look 
later tonight. 

Paul 



On Tue, 20 Apr 2010, nek5000-users at lists.mcs.anl.gov wrote: 

> Hi, 
> 
> I am running into an issue with 'Vanishing Jacobian'. To help understand what the problem 
> is, could someone explain what is meant in the error? Specifically, what it means by "Xth node" of the element. 
> Also, I ran into this issue when I was deforming geometries in the usr file, where one of the elements 
> would overlap another by mistake. However in this case I know there are no overlaps. 
> 
> Here is a portion: 
> 
> 0 ERROR: Vanishing Jacobian near 91th node of element 69. 
> 1.40692804605498586E-002 -7.79619559165757245E-003 
> 0 xyz: 2.65874E-01 3.54498E-01 2.87050E+00 
> 0 xyz: 2.07855E-01 1.77249E-01 2.87050E+00 
> 
> 
> 0 ERROR: Vanishing Jacobian near 76th node of element 70. 
> 2.59472856644434001E-002 -2.12442422718029170E-002 
> 0 xyz: 2.11655E-01 4.23310E-01 2.62500E+00 
> 0 xyz: 3.54498E-01 1.77249E-01 2.87050E+00 
> 
> Thanks for any help deciphering this error! 
> 
> - Michael 
> 
> 
> 
> 
> 
> 
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