what does the continuty residual means??????

jonior · November 12, 2014, 18:01

hi,

in my simulation calculation all the residuals are converging well but the continuity is taken tooooooooo much iterations ???????

can any one tell me to which it refers(what does it mean)
and how can i improve its behavior to minimize the number of iterations

pakk · November 13, 2014, 04:09

For this, the best place to start looking is the help.

HyperNova · November 13, 2014, 12:39

Quote:

Originally Posted by jonior

hi,

in my simulation calculation all the residuals are converging well but the continuity is taken tooooooooo much iterations ???????

can any one tell me to which it refers(what does it mean)
and how can i improve its behavior to minimize the number of iterations

it depends , first check your boundry conditions , uncorrect boundry condition may result to this , what is it exactly you are modelling ? notice that in fluent continuitu is not a solver equation , it is checker equation , sometimes it is not important to converge the continuity !

LuckyTran · November 13, 2014, 18:22

Have you been resetting the residual statistics repeatedly?

The continuity residual is scaled based on the worst mass imbalance encountered in the first 5 iterations. If you initial guess or initial conditions are "good" the worst residual encountered in the first iterations will not be very high. This may give the impression that the continuity residual is not "converging" even though the solution is accurately computed. If you initialize the simulation with the solution, your continuity residual will be stuck at 1. Can this explain your situation?

jonior · November 14, 2014, 14:25

dera lucky,

thanks so much for your help yes this explaining my simulation

i understant from your reply that my simulation is very good estimated?

despite all other residuals are converging until reach E-4, the continuty is almost constant at 1 and nearly E-1

did i understand you right

LuckyTran · November 14, 2014, 20:43

No. It is sufficient though not necessarily true and it is unlikely to be the case. I merely proposed this as an explanation if and you would know if you have been repeatedly resetting the residual statistics or if the initial guess is incredibly accurate. By the way, it would have to be accurate over the whole domain. Resetting the residuals is fairly easy to do by accident.

November 12, 2014, 18:01	what does the continuty residual means??????	#1
jonior New Member Join Date: Sep 2014 Posts: 21 Rep Power: 11	hi, in my simulation calculation all the residuals are converging well but the continuity is taken tooooooooo much iterations ??????? can any one tell me to which it refers(what does it mean) and how can i improve its behavior to minimize the number of iterations

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November 13, 2014, 04:09		#2
pakk Senior Member Join Date: Nov 2013 Posts: 1,965 Rep Power: 26	For this, the best place to start looking is the help.

November 13, 2014, 18:22		#4
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	Have you been resetting the residual statistics repeatedly? The continuity residual is scaled based on the worst mass imbalance encountered in the first 5 iterations. If you initial guess or initial conditions are "good" the worst residual encountered in the first iterations will not be very high. This may give the impression that the continuity residual is not "converging" even though the solution is accurately computed. If you initialize the simulation with the solution, your continuity residual will be stuck at 1. Can this explain your situation?

November 14, 2014, 14:25		#5
jonior New Member Join Date: Sep 2014 Posts: 21 Rep Power: 11	dera lucky, thanks so much for your help yes this explaining my simulation i understant from your reply that my simulation is very good estimated? despite all other residuals are converging until reach E-4, the continuty is almost constant at 1 and nearly E-1 did i understand you right

November 14, 2014, 20:43		#6
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	No. It is sufficient though not necessarily true and it is unlikely to be the case. I merely proposed this as an explanation if and you would know if you have been repeatedly resetting the residual statistics or if the initial guess is incredibly accurate. By the way, it would have to be accurate over the whole domain. Resetting the residuals is fairly easy to do by accident.