simulation stopped

BAssem.at · October 28, 2013, 03:32

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.

October 28, 2013, 03:32	simulation stopped	#1
BAssem.at New Member Athmani Bassem Join Date: Dec 2011 Posts: 14 Rep Power: 15	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. Last edited by BAssem.at; October 29, 2013 at 05:35.

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November 7, 2013, 18:16		#2
dmilano Member Join Date: Mar 2012 Posts: 72 Rep Power: 14	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.

November 11, 2013, 06:15		#3
BAssem.at New Member Athmani Bassem Join Date: Dec 2011 Posts: 14 Rep Power: 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.