Failure in initialization

cshsgy · November 8, 2018, 14:04

Hi all,
I am simulating a simple axisymmetric jet flow. However, when I tried to initialize, a floating point exception error pops up with AMG solver: ads-0.
I surveyed quite a range of discussions online, and there are two types of advice:
1. Have a mesh with higher quality
2. Change the residual tolerance
However, I both refined the mesh and also played with different residual, it seems that no difference is made.
Does anyone know how to solve this problem? Or is there a good tutorial for axisymmetric jet simulation that I can take as an example?
Thanks so much for your help guyz!:P

LuckyTran · November 8, 2018, 18:44

Well none of those recommendations affects initialization.

How are you initializing your case? Some setting there must be blatantly wrong for there to be a floating point error.

RaiderDoctor · November 8, 2018, 21:38

Yeah... I'm with Lucky on this one. If your setup is encountering a floating point exception during initialization, then something major is wrong. Can you provide more info?

cshsgy · November 9, 2018, 00:40

Hi LuckyTran and RaiderDoctor,
I have just read through the related ANSYS official documents... It turns out that the axisymmetric line must lie on x-axis. I think a lot of other guys have made similar error (including some of my friends). Sorry for this sort of novice question and have a nice day!

LuckyTran · November 9, 2018, 08:47

Quote:

Originally Posted by cshsgy

Hi LuckyTran and RaiderDoctor,
I have just read through the related ANSYS official documents... It turns out that the axisymmetric line must lie on x-axis. I think a lot of other guys have made similar error (including some of my friends). Sorry for this sort of novice question and have a nice day!

If you dig deep enough, you'll find a post where I also made the same realization. So yes I agree probably a lot of people have made this mistake. It's somewhat non-intuitive that there is a BC of type axis but the limitation that the actual axis of symmetry lie on x=0 you can only learn by reading the documentation. It would be nice if there is a more gentle reminder in the GUI or message printed to the terminal.

Glad you figured it out.

November 8, 2018, 14:04	Failure in initialization	#1
cshsgy New Member Chen Sihe Join Date: Sep 2017 Posts: 26 Rep Power: 8	Hi all, I am simulating a simple axisymmetric jet flow. However, when I tried to initialize, a floating point exception error pops up with AMG solver: ads-0. I surveyed quite a range of discussions online, and there are two types of advice: 1. Have a mesh with higher quality 2. Change the residual tolerance However, I both refined the mesh and also played with different residual, it seems that no difference is made. Does anyone know how to solve this problem? Or is there a good tutorial for axisymmetric jet simulation that I can take as an example? Thanks so much for your help guyz!:P

November 9, 2018, 00:40		#4
cshsgy New Member Chen Sihe Join Date: Sep 2017 Posts: 26 Rep Power: 8	Hi LuckyTran and RaiderDoctor, I have just read through the related ANSYS official documents... It turns out that the axisymmetric line must lie on x-axis. I think a lot of other guys have made similar error (including some of my friends). Sorry for this sort of novice question and have a nice day! duanwuCHEN likes this.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
FMG initialization query	Mohsin	FLUENT	6	November 2, 2016 02:02
CFX Transient Initialization	frossi	CFX	1	June 17, 2016 09:31
Full Multigrid Initialization	Mr.Goodcat	FLUENT	0	March 17, 2016 06:43
Hybrid Initialization Failure	Persil	FLUENT	2	April 23, 2014 17:57
Pressure initialization Failure.	Nalleli	Siemens	2	August 31, 2005 06:28

November 8, 2018, 18:44		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 65	Well none of those recommendations affects initialization. How are you initializing your case? Some setting there must be blatantly wrong for there to be a floating point error.

November 8, 2018, 21:38		#3
RaiderDoctor Senior Member Join Date: Dec 2016 Posts: 152 Rep Power: 10	Yeah... I'm with Lucky on this one. If your setup is encountering a floating point exception during initialization, then something major is wrong. Can you provide more info?