[Nek5000-users] logfile

Fri Mar 30 07:05:29 CDT 2018

       1520  Hmholtz TEMP      12   3.8789E-11   4.5120E+07   1.0000E-10

On Step 1520, it took 12 iterations to reach a residual of 3.8e-11, starting with a residual of 4.5e7, with target residual 1.e-10.

[ This is actually too tight of a tolerance, since you are asking for 17 orders of magnitude reduction in residual and are working only with 16 significant digits. It seems like you might need to change your .rea file in the following way:

       set p21 and p22 to 0

       set p24, tolrel , to 1.e-3

       set p25, tolabs, to 1.e-3

The only time you'll need tolrel/abs tighter than this is if you're doing an analytic convergence study where you know the answer to an infinite number of digits.   For engineering calculations, 1.e-2 to 1.e-3 is fine.   The residual tolerances are set conservatively based on these input values.

  1520  Helmh3 fluid      17   3.6594E-11   4.7524E-01   1.0000E-10
       1520  U-PRES gmres     120   1.3494E-08   4.5675E-06
1.0000E-10   7.8799E-01   3.0171E+00

You have 17 iterations for the moment equations.

You have 120 iterations for pressure.   Again, your tolerances are too tight for engineering calculations -- you do not need 1.e-10 for divergence (i.e., for the pressure residual tolerance).

hth,

Paul

________________________________
From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
Sent: Friday, March 30, 2018 4:52:26 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] logfile

The following is my logfile entry (sample lines). The first line is
understandable. What do the values in the third and following lines
denote?

------------------------------------------------------
Step   1520, t= 7.6000000E-02, DT= 5.0000000E-05, C=  0.072 5.3831E+03
3.5403E+00
             Solving for Hmholtz scalars
       1520  Hmholtz TEMP      12   3.8789E-11   4.5120E+07   1.0000E-10
       1520  Scalars done  7.6000E-02  8.3823E-02
             Solving for fluid
       1520  Helmh3 fluid      17   3.6594E-11   4.7524E-01   1.0000E-10
       1520  U-PRES gmres     120   1.3494E-08   4.5675E-06
1.0000E-10   7.8799E-01   3.0171E+00
       1520  Fluid done  7.6000E-02  3.3650E+00
--------------------------------------------------------

On Fri, Mar 30, 2018 at 3:05 PM,  <nek5000-users at lists.mcs.anl.gov> wrote:
> I am not sure what you are talking about?
>
> -----Original message-----
>> From:nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
>> Sent: Friday 30th March 2018 10:30
>> To: nek5000-users at lists.mcs.anl.gov
>> Subject: [Nek5000-users] logfile
>>
>> Hi Neks,
>>
>>      What are the entries in the logfile that is output from running
>> the code.  Please let me know where the entries are determined in the
>> code.
>>
>> Thanks
>> Swarandeep
>> _______________________________________________
>> 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
_______________________________________________
Nek5000-users mailing list
Nek5000-users at lists.mcs.anl.gov
https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20180330/d30887ad/attachment.html>