[Nek5000-users] **ERROR**: Failed in HMHOLTZ

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

Hi Aleks, following your advice, it works. Thank you very much!

Wei

2014-11-06 12:31 GMT+01:00 <nek5000-users at lists.mcs.anl.gov>:

>  P.S. Sorry, correction -- I meant you should increase your p22 from
> 1e-16 to. say 1.e-12 but you will also need to keep p21 at least 1 or 2
> order of magnitude higher, say 1.e-10
>
> Aleks
>  ------------------------------
> *From:* nek5000-users-bounces at lists.mcs.anl.gov [
> 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:* Thursday, November 06, 2014 5:28 AM
> *To:* nek5000-users at lists.mcs.anl.gov
> *Subject:* Re: [Nek5000-users] **ERROR**: Failed in HMHOLTZ
>
>   Hi Wei,
>
> Your Helmholtz tolerance of 1e-16 is too high (p22) -- velocity components
> start an interation from 5...4.e-2 residuals and converge to 4...2.e-16.
>
> Once you lower it, make sure the Divergence tolerance (p21) is still an
> order or 2 magnitude higher.
>
> Aleks
>  ------------------------------
> *From:* nek5000-users-bounces at lists.mcs.anl.gov [
> 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:* Thursday, November 06, 2014 5:21 AM
> *To:* nek5000-users at lists.mcs.anl.gov
> *Subject:* [Nek5000-users] **ERROR**: Failed in HMHOLTZ
>
>   Hi Neks
>
>  when I setup a profile 2D flow, there are informations like this, but
> the simulation is not crash,
>
>   Step    800, t= 8.0000000E-02, DT= 1.0000000E-04, C=  0.431 9.2444E+03
> 1.0117E+01
>  Solving for fluid F T T
>    800   100 **ERROR**: Failed in HMHOLTZ: VELX   3.7727E-16   5.3129E-02
>   1.0000E-16
>    800   100 **ERROR**: Failed in HMHOLTZ: VELY   2.4683E-16   3.5181E-02
>   1.0000E-16
>        800 U-PRES gmres:     23  5.6827E-15  1.0000E-14  9.6473E-07
> 9.5640E-01  2.4052E+00
>         800   8.0000E-02  1.0044E+01 Fluid done
>      800  8.00000000000E-02  6.70022578679E-01  1.99103625323E-01
> 4.70918953356E-01      1dragx
>      800  8.00000000000E-02  4.12612202513E-01  5.10664067531E-01
> -9.80518650173E-02      1dragy
>  dump history points
>  done :: dump history points
>
>
>  The CFL number is below than 0.5 already, the polynomial order is 7 in
> this case. when I choose a lower order p, this information will be
> disappeared after several  iteration steps.  I have checked the mesh looks
> fine, the parameters setting are copied from “ext_cyl”  with a smaller
> values of p21 to p25, I  don’t know what is wrong, should I ignore ?
>
>  thanks,
>
>  Wei
>
>
> _______________________________________________
> 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/20141106/3e67e5a7/attachment-0001.html>