[Nek5000-users] Error in Hmholtz solving

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

Dear Neks,


I'm getting the error message of '**ERROR**: Failed in HMHOLTZ: ' when running my simulation. I've checked the subroutine 'cggo' in hmholtz.f where the error message is printed. I understand that when the tolerance is not satisfied, the code would output this error message. But what I'm wondering is why the maximum iteration number is only 100. In the subroutine 'cggo', niter is equal to min(maxit,maxcg) where maxit=200 and maxcg=900. I can't see other places where maxit is restricted to only 100. So why the maximum iteration number is 100 when solving the Hmholtz equation?


Also, is it right that if I increase the maximum number of iterations to certain point where the tolerance is satisfied, I won't get the error message?


Hope anyone can help me on this. Thank you very much in advance.


Best regards,

Tony


Example of the error message:

Step     52, t= 2.5600000E+01, DT= 5.0000000E-02, C=  2.689 5.6747E+02 1.0237E+01
 Solving for fluid T T T
       52 PRES gmres:   29  9.7057E-07  1.0000E-06  1.5219E-03  1.0926E+00  2.1480E+00    F
         52    Hmholtz VELX:     99   8.5954E-10   6.0898E-03   1.0000E-09
    52   100 **ERROR**: Failed in HMHOLTZ: VELY   1.7088E-09   2.5049E-02   1.0000E-09
    52   100 **ERROR**: Failed in HMHOLTZ: VELZ   1.4665E-09   2.5165E-02   1.0000E-09
               L1/L2 DIV(V)    :   2.7573E-18   9.1661E-04
               L1/L2 QTL       :   0.0000E+00   0.0000E+00
               L1/L2 DIV(V)-QTL:   2.7573E-18   9.1661E-04
         52   2.5600E+01  1.0094E+01 Fluid done
Step     53, t= 2.5650000E+01, DT= 5.0000000E-02, C=  2.697 5.7766E+02 1.0186E+01
 Solving for fluid T T T
       53 PRES gmres:   28  9.6076E-07  1.0000E-06  1.1322E-03  1.0558E+00  2.0542E+00    F
         53    Hmholtz VELX:     98   9.4891E-10   5.8783E-03   1.0000E-09
    53   100 **ERROR**: Failed in HMHOLTZ: VELY   1.6450E-09   2.4941E-02   1.0000E-09
    53   100 **ERROR**: Failed in HMHOLTZ: VELZ   1.4160E-09   2.5049E-02   1.0000E-09
               L1/L2 DIV(V)    :   2.4695E-18   1.0845E-03
               L1/L2 QTL       :   0.0000E+00   0.0000E+00
               L1/L2 DIV(V)-QTL:   2.4695E-18   1.0845E-03
         53   2.5650E+01  9.9794E+00 Fluid done
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