[Nek5000-users] Vanishing Jacobian error description

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

Michael,

I looked at this for a couple of different N.

nek/postx think that the geometry is messed up ---

   see  www.mcs.anl.gov/~fischer/zzz.jpg

That being said, it could easily be a problem w/ the midside
node support that I added last month.   (NOTE: to see the
geometry I had to fix something in the nek code -- normally
when you get vanishing jacobian the code will output "xyzblah.fld01"
with the geometry, so that you can then look at this in postx or
visit.  For pn/pn, this was broken but is now working in the 
just-updated repo.)

Do you have a way to verify that your lofting is working?

Paul


On Wed, 21 Apr 2010, nek5000-users at lists.mcs.anl.gov wrote:

> Hi,
>
> Sorry, yes that was for without the curve side data. Here is the case that includes the curved side data.
>
> - Michael
>
> ----- Original Message -----
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov
> Sent: Wednesday, April 21, 2010 8:39:38 AM GMT -06:00 Guadalajara / Mexico City / Monterrey
> Subject: Re: [Nek5000-users] Vanishing Jacobian error description
>
> The case you sent runs fine.... is it w/ or w/o the curved side info? Paul On Wed, 21 Apr 2010, nek5000-users at lists.mcs.anl.gov wrote: > > > 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" > Sent: Tuesday, April 20, 2010 3:36:44 PM GMT -06:00 U
 S/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+0
 0 >> 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 >> >> >> >> >> >> > _______________________________________________ > Nek5000-users mailing list > Nek5000-users at lists.mcs.anl.gov > https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users >
> _______________________________________________ Nek5000-users mailing list Nek5000-users at lists.mcs.anl.gov https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users