[Nek5000-users] Helmholtz error

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

Hi nek users,

I'm getting an error I don't understand, perhaps someone can help.  I'm
simulating the Boussinesq equations in a 2D box of aspect ratio 2 with
periodic side BC, stress-free velocity and fixed-flux temperature on the top
and bottom, and at a Rayleigh number of 10^8.  My time step is 2^-6; and
longer and there are CFL problems. The part of the logfile where the error
first appears is below.  Any idea?

Thanks a lot,

David


        321    Hmholtz VELX:      1   1.8722E-04   9.4841E-04   3.0177E-02
   321  5.5836E+03  3.0971E-03  1.8028E+06    16 alph1x
   321 halpha  16  9.1147E+00  1.6433E-01  1.6202E-03  1.5295E-03
 3.2457E-04  9.6963E-05  5.3573E-05  2.3766E-05  1.5049E-05  1.1283E-05

        321    Hmholtz VELY:      1   4.5111E-04   3.0971E-03   3.0177E-02
  321   16 alpha:  4.3959E-02  1.3360E-03  1.2680E-04  6.4401E-06
-3.8972E-06  3.2052E-06  7.4030E-06  3.4569E-06  2.8993E-06  1.4221E-06
   321  16  3.5585E-04  1.2617E-07  2.8203E+03 alph12
        321    U-Pres gmres:        3   2.6567E-09   4.1491E-09   1.2617E-07
  1.5726E-03   2.5913E-03
 321  DNORM, DIVEX 7.71505530689053011E-6 2.65666629955944499E-9
        321   6.4200E-04  6.4809E-03 Fluid done
      321  6.420000E-04  7.911223E-01  1.711772E+00 umax
     321  0.6420E-03 t_av= 0.5000E+00 Ek= 0.1953E+00 Nu= 0.1000E+01
Step    322, t= 6.4400000E-04, DT= 2.0000000E-06, C=  0.000 5.4661E+00
9.7695E-03
             Solving for heat
             Solving for fluid
        322    Hmholtz TEMP:      1   9.9844E-03   6.0396E-01   2.4836E-02
        322   6.4400E-04  1.0539E-03 Heat done
   322  2.0339E+03  5.8756E-03  3.4616E+05    17 alph1x
   322 halpha  17  3.3193E+00  1.0787E-01  5.3974E-04  9.8243E-04
 3.7291E-04  2.3705E-04  5.1605E-05  3.4660E-05  1.1899E-05  1.1993E-05

        322    Hmholtz VELX:      1   1.2039E-03   5.8756E-03   3.0705E-02
   322  5.6870E+03         NaN         NaN    17 alph1x
   322 halpha  17  9.2834E+00  1.7756E-01  1.8590E-03  1.7684E-03
 3.7603E-04  1.1302E-04  6.3138E-05  2.9137E-05  1.9115E-05  1.5046E-05

   322  5000 **ERROR**: Failed in HMHOLTZ: VELY          NaN          NaN
3.0705E-02
  322   17 alpha:         NaN         NaN         NaN         NaN
NaN         NaN         NaN         NaN         NaN         NaN
   322  17         NaN         NaN         NaN alph12
        322    U-Pres gmres:      100          NaN   4.1491E-09          NaN
  5.2696E-02   8.8512E-02
 322  DNORM, DIVEX NaN NaN
        322   6.4400E-04  6.0996E-01 Fluid done
      322  6.440000E-04 -9.900000E+21 -9.900000E+21 umax
     322  0.6440E-03 t_av= 0.5000E+00 Ek=        NaN Nu=        NaN
Step    323, t= 6.4600000E-04, DT= 2.0000000E-06, C=  0.000 6.0793E+00
6.1319E-01
             Solving for heat
             Solving for fluid
   323  5000 **ERROR**: Failed in HMHOLTZ: TEMP          NaN          NaN
2.4836E-02
        323   6.4600E-04  5.2047E-01 Heat done
   323         NaN         NaN         NaN    18 alph1x
   323 halpha  18         NaN         NaN         NaN         NaN
NaN
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