[Nek5000-users] Vanishing Jacobians while using moving mesh

Tue Feb 14 08:08:35 CST 2012

Hi Neks,

I'm trying to simulate 2D flow over an oscillating cylinder using moving
mesh, and tried to set up a test case by looking at the peris example. I
however am getting vanishing Jacobians after the first few timesteps.

I am modifying the the boundary velocity of the cylinder in userbc instead
of userchk (as in the peris example). Would it be possible for you to look
at my .usr file and tell me what I am doing wrong?

I have attached the .rea, .usr, and SIZE with this mail.

Further, when I try to view the mesh of the output (or the xyz fld
outputfile) in visit, visit crashes with the following error:
VisIt's viewer exited abnormally! Aborting the Graphical User Interface.

Lastly, would it be possible to simulate moving walls with large
deformations (i.e. where multiple elements get deformed), where the
deformation is known ahead of time? (eg. a flapping aerofoil)

Thank you for your help!

Regards,
Pradeep

Extract from logfile:

        60 U-PRES gmres:    100  7.5345E+42  1.0000E-02  4.0062E+57
6.7556E-03  1.5093E-02
 ERROR:  alphad .le. 0 in econjp -1.31175831444004495E+179          16
 ERROR:  alphad .le. 0 in econjp -1.31175831444004495E+179          16
 ERROR:  alphad .le. 0 in econjp -1.31175831444004495E+179          16
 ERROR:  alphad .le. 0 in econjp -1.31175831444004495E+179          16
          60  DNORM, DIVEX  1.18120867781751263E+043
7.53448962619089522E+042
         60   6.0000E-02  1.6697E-02 Fluid done
     DT/DTCFL/DTFS/DTINIT   0.635E-45   0.635E-45   0.000E+00   0.100E-02
Step     61, t= 6.0800000E-02, DT= 8.0000000E-04, C=******* 2.2667E-01
1.8287E-02
             Solving for fluid

    3  ERROR:  Vanishing Jacobian near      2th node of element         3.

    2  ERROR:  Vanishing Jacobian near      2th node of element         1.
  2.27348348709230109E+081 -5.12478988977734591E+080
 -2.60483379627720531E+079  3.21465902039155941E+039
    3 xyz:  -5.30056E+39  -5.84642E+39
    3 xyz:  -5.24850E+39  -6.93109E+39

    3  ERROR:  Vanishing Jacobian near      2th node of element         4.
    2 xyz:   1.25061E+38   4.64957E+39
  9.79493533554062390E+080 -3.01548938509156252E+080
    2 xyz:  -2.46589E-08  -5.64092E-01

    3 xyz:  -5.30056E+39  -5.84642E+39
    3 xyz:  -5.24850E+39  -6.93109E+39
    2  ERROR:  Vanishing Jacobian near      3th node of element         2.

    3  ERROR:  Vanishing Jacobian near      2th node of element         5.
  1.43125817410005932E+039 -6.03607926692375119E+038
  5.54918579647991880E+039 -1.67302572815141788E+039
    3 xyz:  -5.30056E+39  -5.84642E+39
    2 xyz:  -2.46589E-08  -5.64092E-01
    3 xyz:  -5.24850E+39  -6.93109E+39

    3  ERROR:  Vanishing Jacobian near      2th node of element         6.
    2 xyz:  -3.07794E-08  -7.04112E-01

    2  ERROR:  Vanishing Jacobian near      7th node of element         7.
  8.35923896949543198E+038 -3.55455289325888722E+038
    3 xyz:  -5.30056E+39  -5.84642E+39
  1.21747337192549314E+039 -1.79454406120891328E+038
    3 xyz:  -5.24850E+39  -6.93109E+39
    2 xyz:  -5.66434E-08  -1.29581E+00
    2 xyz:  -6.27639E-08  -1.43583E+00

    2  ERROR:  Vanishing Jacobian near      9th node of element         8.
  1.17802538305091326E+039 -4.21489851051369387E+038
    2 xyz:  -6.55671E-08  -1.49996E+00
    2 xyz:  -3.25016E+38   4.93026E+39
 call outfld: ifpsco: F

       61  6.0800E-02 Write checkpoint:

       61  6.0800E-02 OPEN:
xyzcyl2.fld01

 Jac error 1, setting p66=4, ifxyo=t

call exitt: dying ...
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