Divergence detected in AMG solver

Musa · March 3, 2012, 17:47

My simulation has broken down and i am receiving a message saying divergence detected in AMG solver:vof1-increasing relaxation sweeps. Anyone help me

cfd seeker · March 4, 2012, 06:47

Mate reduce the courant no and also the under relaxation factors at the start of simulation, once your solution gets stabilized then increase the courant no. The low the courant no. the more your solution will be stabilized but solution will take longer time to converge and vice-versa

Musa · March 4, 2012, 10:15

cfd seeker thanx for your suggestion but i am using the implicit solution so the courant number is not applicable and yes i have tried to reduce the under relaxation factors but it has not of much help.

cfd seeker · March 4, 2012, 13:40

Implicit scheme is very very unstable and has very strict conditions on the time step size. Courant no can be changed in the implicit scheme also. Its default value is 1 and you can reduce it.

March 3, 2012, 17:47	Divergence detected in AMG solver	#1
Musa Member Musango Lungu Join Date: Dec 2011 Location: China Posts: 73 Rep Power: 14	My simulation has broken down and i am receiving a message saying divergence detected in AMG solver:vof1-increasing relaxation sweeps. Anyone help me

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March 4, 2012, 06:47		#2
cfd seeker Senior Member Join Date: Mar 2011 Location: Germany Posts: 552 Rep Power: 20	Mate reduce the courant no and also the under relaxation factors at the start of simulation, once your solution gets stabilized then increase the courant no. The low the courant no. the more your solution will be stabilized but solution will take longer time to converge and vice-versa

March 4, 2012, 10:15		#3
Musa Member Musango Lungu Join Date: Dec 2011 Location: China Posts: 73 Rep Power: 14	cfd seeker thanx for your suggestion but i am using the implicit solution so the courant number is not applicable and yes i have tried to reduce the under relaxation factors but it has not of much help.

March 4, 2012, 13:40		#4
cfd seeker Senior Member Join Date: Mar 2011 Location: Germany Posts: 552 Rep Power: 20	Implicit scheme is very very unstable and has very strict conditions on the time step size. Courant no can be changed in the implicit scheme also. Its default value is 1 and you can reduce it.