CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLOW-3D (http://www.cfd-online.com/Forums/flow-3d/)
-   -   simulation stopped (http://www.cfd-online.com/Forums/flow-3d/125547-simulation-stopped.html)

BAssem.at October 28, 2013 04:32

simulation stopped
 
Dear all,
i have simulation stopped with this error message:
Preprocessor Messages:
convective flux exceeded stability limit
at t= 2.9323E-02 cycle= 1 iter= 1 delt= 2.9323E-02 mesh block 1
restarting cycle with smaller time step



convection failure diagnostics
time, cycle, delt, iter = 2.9323E-02 1 2.9323E-02 1
maximum failure ratio = 5.74337E+00 is in x-coordinate direction
at cell ( 458, 33, 2) mesh block 1

i j k u v w p f tn nf
afr afb aft vf

458, 33, 1 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
(old) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0
0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
458, 32, 2 7.7217E+00 0.0000E+00 -2.8766E-01 0.0000E+00 1.1827E+00
(old) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 9.9959E-01 0.0000E+00 1
1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00
457, 33, 2 7.4346E+00 0.0000E+00 -1.8974E-01 1.1682E+04 1.1205E+00
(old) 0.0000E+00 0.0000E+00 0.0000E+00 5.1670E+04 1.0000E+00 0.0000E+00 0
1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00
458, 33, 2 7.7217E+00 0.0000E+00 -2.8766E-01 0.0000E+00 1.1827E+00
(old) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 9.9959E-01 0.0000E+00 1
1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00
459, 33, 2 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 9.9284E-01
(old) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 8
1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00
458, 34, 2 7.7217E+00 0.0000E+00 -2.8766E-01 0.0000E+00 1.1827E+00
(old) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 9.9959E-01 0.0000E+00 1
1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00
458, 33, 3 7.3374E+00 0.0000E+00 -2.8766E-01 0.0000E+00 1.0000E+00
(old) 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 9.9959E-01 0.0000E+00 1
1.0000E+00 1.0000E+00 1.0000E+00 1.0000E+00






============= mentor tip ===============
persistent f-packing location at t= 0.11645E+00
x= 0.64725E+01, y= 0.23108E-01, z= 0.21000E+01
i= 421, j= 2, k= 47
f= 0.97129E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.16183E+00
x= 0.64725E+01, y= 0.27960E+01, z= 0.21000E+01
i= 421, j= 62, k= 47
f= 0.97633E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.17752E+00
x= 0.64725E+01, y= 0.28422E+01, z= 0.21000E+01
i= 421, j= 63, k= 47
f= 0.97733E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.20453E+00
x= 0.64725E+01, y= 0.53147E+00, z= 0.21000E+01
i= 421, j= 13, k= 47
f= 0.97911E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.23177E+00
x= 0.64725E+01, y= 0.48526E+00, z= 0.21000E+01
i= 421, j= 12, k= 47
f= 0.97972E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.26053E+00
x= 0.64725E+01, y= 0.43904E+00, z= 0.21000E+01
i= 421, j= 11, k= 47
f= 0.98040E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.36301E+00
x= 0.64725E+01, y= 0.57769E+00, z= 0.21000E+01
i= 421, j= 14, k= 47
f= 0.98599E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.45597E+00
x= 0.64725E+01, y= 0.27960E+01, z= 0.21000E+01
i= 421, j= 62, k= 47
f= 0.98883E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.59428E+00
x= 0.64725E+01, y= 0.27498E+01, z= 0.21000E+01
i= 421, j= 61, k= 47
f= 0.98957E+00
========================================

recommend reducing cfpk by factor of 10


============= mentor tip ===============
persistent f-packing location at t= 0.67306E+00
x= 0.64725E+01, y= 0.27498E+01, z= 0.21000E+01
i= 421, j= 61, k= 47
f= 0.98984E+00
========================================

recommend reducing cfpk by factor of 10

can someone explain to me this message.
many thanks!
Bassem.

dmilano November 7, 2013 18:16

The "persistent f-packing location" means that the f-packing algorithm has been active in that particular cell for the last 10 consecutive computational cycles. This may be an indicator that the f-packing algorithm is trying to close voids in the fluid that should physically be opening. The best thing to do is look at the results and decide if they make sense. If not, then try reducing the strength of the f-packing adjustment.

BAssem.at November 11, 2013 06:15

Thank you for your interest dmilano.
I found a void in the figure. I treated him by increasing the number of cells. In the end, I got acceptable results.
thanks a lot again for the explanation.


All times are GMT -4. The time now is 16:14.