[Nek5000-users] Restart using rea

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

The usual first step here is to restart with a lower value of dt.


In this case, I would recommend reducing dt by about a factor of 5 or

10 and seeing if this survives with a reasonable Courant number.


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: Wednesday, August 1, 2018 10:16:37 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Restart using rea


Dear Nek users,



I ran into a problem when restarting using the .rea file. In the .rea file, I specified the name of the file (the file was renamed from the last time step of the previous simuiatlion)to restart with:



  ***** NO THERMAL BOUNDARY CONDITIONS *****

            1 PRESOLVE/RESTART OPTIONS  *****

restart.fld



Without changing the time step size, I restarted the simulation, but I received an error:



Step    581, time= 3.0955000E+02, DT= 5.0000000E-02, C=  4.240 4.3486E+01 1.1724E-01

             Solving for fluid

        581  Hmholtz VELX      12   1.5661E-12   7.4073E-01   5.0000E-12

        581  Hmholtz VELY      11   9.6329E-13   3.3660E+00   5.0000E-12

        581  Project PRES           5.5975E-05   1.6744E+00   2.9913E+04  13  20

        581  U-PRES gmres     120   6.1973E-10   1.8658E-06   5.0000E-12   4.3239E-02   1.0688E-01

        581  Fluid done  3.0955E+02  1.1453E-01

     581  3.09550E+02  6.46747E+01  0.00000E+00  7.53982E+02  blasius: delta*

CFL, Ctarg!   7.39542251238818       0.500000000000000



The original CFL was only 0.028 or so, after restart, it fluctuates significantly and eventually it quits for CFL being too large. Could anyone help me on this please?



Many thanks
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