[Nek5000-users] Problem in obtaining eigenvalues through Arnoldi (using NEK5000 with the ARPACK library)
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Thu Jul 12 03:07:59 CDT 2018
Hi Neks
I am running a 3D simulation for a flow over a cylinder. My domain size
for simulation is 100Dx100D. where D is the diameter of a cylinder. We have
obtained the base flow through SFD. The base flow is used to calculate the
stability analysis through NEK5000 with the ARPACK library (Implemented by
A. Peplinski).
we have used the following parameters.....
90.0000 p111 : ARNOLDI: size of Krylov space
30.0000 p112 : ARNOLDI: number of eigenvectors
We have run the Arnoldi with restart but we are not able to get the output
file (eigenvalues.txt and egvext_cyl0.f0..) even after almost 20 restarts.
Also, we tried to run with increasing the size of Krylov space but the
eigenvalues are not converging.
The log file shows no changes in converged ritz values after around 20-22
values.
The part of the log file is shown below...........
Kindly, help me out and let me know where I am going wrong.....
Alok Mishra
---------------------------------------------------------------------------------------------------------------
ARNOLDI: after 520 stepper phase
_naup2: Corresponding B-norm of the residual
--------------------------------------------
1 - 1: 6.623D-01
_naup2: no. of "converged" Ritz values at this iter.
----------------------------------------------------
1 - 1: 22
_naup2: NEV and NP are
----------------------
1 - 2: 52 128
_naup2: "wanted" Ritz values -- real part
-----------------------------------------
1 - 5: 9.905D-01 9.905D-01 9.854D-01 9.854D-01 9.855D-01
6 - 10: 9.855D-01 9.897D-01 9.897D-01 9.924D-01 9.930D-01
11 - 15: 9.930D-01 9.905D-01 9.905D-01 9.943D-01 9.943D-01
16 - 20: 9.938D-01 9.938D-01 9.948D-01 9.948D-01 9.949D-01
21 - 25: 9.949D-01 9.951D-01 9.958D-01 9.960D-01 9.962D-01
26 - 30: 9.962D-01 9.966D-01 9.970D-01 9.970D-01 9.969D-01
31 - 35: 9.969D-01 9.973D-01 9.974D-01 9.975D-01 9.976D-01
36 - 40: 9.976D-01 9.971D-01 9.971D-01 9.978D-01 9.979D-01
41 - 45: 9.979D-01 9.982D-01 9.982D-01 1.000D+00 9.908D-01
46 - 50: 9.908D-01 1.004D+00 1.004D+00 1.005D+00 1.005D+00
51 - 52: 1.006D+00 1.006D+00
_naup2: "wanted" Ritz values -- imag part
-----------------------------------------
1 - 5: 5.038D-02 -5.038D-02 -1.127D-01 1.127D-01 -1.119D-01
6 - 10: 1.119D-01 6.954D-02 -6.954D-02 0.000D+00 3.705D-03
11 - 15: -3.705D-03 -7.103D-02 7.103D-02 -9.233D-04 9.233D-04
16 - 20: 4.345D-02 -4.345D-02 6.799D-04 -6.799D-04 -1.821D-02
21 - 25: 1.821D-02 0.000D+00 0.000D+00 0.000D+00 -2.047D-03
26 - 30: 2.047D-03 0.000D+00 7.200D-05 -7.200D-05 2.386D-02
31 - 35: -2.386D-02 0.000D+00 0.000D+00 0.000D+00 -1.140D-04
36 - 40: 1.140D-04 3.125D-02 -3.125D-02 0.000D+00 -1.248D-04
41 - 45: 1.248D-04 -1.673D-03 1.673D-03 0.000D+00 -1.508D-01
46 - 50: 1.508D-01 -1.863D-02 1.863D-02 -2.109D-02 2.109D-02
51 - 52: -1.152D-02 1.152D-02
_naup2: Ritz estimates of the "wanted" values
----------------------------------------------
1 - 5: 3.315D-02 3.315D-02 3.244D-05 3.244D-05 7.035D-05
6 - 10: 7.035D-05 6.072D-11 6.072D-11 1.314D-02 2.772D-06
11 - 15: 2.772D-06 6.796D-15 6.796D-15 9.719D-04 9.719D-04
16 - 20: 7.467D-17 7.467D-17 5.506D-04 5.506D-04 2.437D-16
21 - 25: 2.437D-16 2.977D-03 7.238D-04 6.054D-04 3.914D-11
26 - 30: 3.914D-11 1.827D-04 1.138D-04 1.138D-04 1.048D-16
31 - 35: 1.048D-16 1.198D-04 6.358D-05 3.013D-05 3.490D-07
36 - 40: 3.490D-07 9.960D-18 9.960D-18 1.340D-07 2.518D-10
41 - 45: 2.518D-10 1.827D-16 1.827D-16 1.781D-16 7.278D-17
46 - 50: 7.278D-17 0.000D+00 0.000D+00 0.000D+00 0.000D+00
51 - 52: 0.000D+00 0.000D+00
Reached max iteration number; settingido=-2 for checkpointing.
ARNOLDI:
IDOARP = -2
Writing checkpoint
0 40 OPEN: ARPm11800.f00002
0 40 OPEN: ARVm11800.f00002
40 2.0000E-01 done :: Write checkpoint
file size = 621.E+00MB
avg data-throughput = 624.1MB/s
io-nodes = 1
ARNOLDI: finalize
Number of stepper cycles 520
Time spent in ARNOLDI 60.3302609920502
Average stepper phase time 10.9141681075096
call outfld: ifpsco: F
40 2.0000E-01 Write checkpoint:
0 40 OPEN: m11800.f00001
40 2.0000E-01 done :: Write checkpoint
file size = 4.0 MB
avg data-throughput = 303.2MB/s
io-nodes = 1
end of time-step loop
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