cfx solver stop in ansys workbench

behrouz · January 3, 2017, 01:11

hi to all
i try to simulate wet natural gas in compressor and it take too long to converge,after i click on "stop" button solver stop itterations and tables appears that show min and max values for different part and variables but the final sentence " The ansys solver finished" (maybe its a little different sentence) did not show up and in ansys workbench cfx can not update (green check did not show up). this situation goes on until i kill ansys in task manager and when i open it again a masseage show up and after that every thing gone!!!
i try small itteration number maybe solver stop automatically but this issue happen again.
how can i force stop solver without crashing and postprocessing??

tnx

evcelica · January 3, 2017, 15:23

Use the stop run in the CFX solver manager, not the workbench one. I try to use workbench as little as possible because of bugs like this.

behrouz · January 4, 2017, 02:09

tnx Erik for reply
is it possible this issue relate to the relative humidity modeling???
when i remove water from the gas solver stop normally,when i change the mass fraction to lower value depend on how decrease it solver run and stop normally or different error happen,i know it seem ridicule but happened to me

ghorrocks · January 4, 2017, 17:20

Your humidity model is causing a numerical instability which is making the solver diverge. So it does not matter how you run the solver (stand-alone, or from workbench) you will always diverge.

The error reported in the first post is that if you run CFX inside workbench, when the solver stops for an unexpected reason (such as divergence) the workbench environment is not very good at picking up the error and handling it properly. If you want to find what the root cause of the problem is you have to look in the CFX output file. Often you have to do a bit of digging to find this file, it is a bit hidden sometimes.

This is why many experienced users do not run CFX inside workbench. As Erik says, you get better knowledge of what is going on if you run CFX stand-alone.

January 3, 2017, 01:11	cfx solver stop in ansys workbench	#1
behrouz Member behrouz Join Date: Mar 2015 Posts: 34 Rep Power: 11	hi to all i try to simulate wet natural gas in compressor and it take too long to converge,after i click on "stop" button solver stop itterations and tables appears that show min and max values for different part and variables but the final sentence " The ansys solver finished" (maybe its a little different sentence) did not show up and in ansys workbench cfx can not update (green check did not show up). this situation goes on until i kill ansys in task manager and when i open it again a masseage show up and after that every thing gone!!! i try small itteration number maybe solver stop automatically but this issue happen again. how can i force stop solver without crashing and postprocessing?? tnx

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January 3, 2017, 15:23		#2
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,167 Rep Power: 23	Use the stop run in the CFX solver manager, not the workbench one. I try to use workbench as little as possible because of bugs like this.

January 4, 2017, 02:09		#3
behrouz Member behrouz Join Date: Mar 2015 Posts: 34 Rep Power: 11	tnx Erik for reply is it possible this issue relate to the relative humidity modeling??? when i remove water from the gas solver stop normally,when i change the mass fraction to lower value depend on how decrease it solver run and stop normally or different error happen,i know it seem ridicule but happened to me

January 4, 2017, 17:20		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Your humidity model is causing a numerical instability which is making the solver diverge. So it does not matter how you run the solver (stand-alone, or from workbench) you will always diverge. The error reported in the first post is that if you run CFX inside workbench, when the solver stops for an unexpected reason (such as divergence) the workbench environment is not very good at picking up the error and handling it properly. If you want to find what the root cause of the problem is you have to look in the CFX output file. Often you have to do a bit of digging to find this file, it is a bit hidden sometimes. This is why many experienced users do not run CFX inside workbench. As Erik says, you get better knowledge of what is going on if you run CFX stand-alone.