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June 26, 2012, 10:46 |
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#21 |
Member
Peter Galimutti
Join Date: May 2012
Posts: 37
Rep Power: 14 |
i got this error few days ago! then I used a different computer and it worked, besides problem setup, it seems to me that it might be because of some missing files or memory problems. the other computer is a server and it just worked fine. try re-installing ansys or increase your system resources.
in the solver manager increase the memory allocation from default 1.0 to 2.0 |
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June 26, 2012, 11:17 |
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#22 |
Senior Member
Join Date: Jul 2011
Location: Berlin, Germany
Posts: 173
Rep Power: 15 |
For me it still sounds like wrong BC settings or maybe even domain initialisations. The fact that cfx is running and trying to place a wall on the inlet to prevent flow from flowing OUT does not sound like files missing or insufficient memory but simply physically wring boundary conditions.
shanxuewenjdx maybe you could specify how you defined the BC's (inlet/outlet etc.)??? and the domain initialisations? Just wondering if you maybe have defined a higher pressure on the opening side than on the inlet side wich would cause a "reverse" flow...presuming that your gears are able to rotate and are not static. |
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June 26, 2012, 12:00 |
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#23 |
Member
Luis Filipe Fabiani
Join Date: Apr 2009
Posts: 43
Rep Power: 17 |
Stefan, maybe this thread helps: http://www.cfd-online.com/Forums/cfx...fx-solver.html
Glenn was suggesting that maybe the solver has diverged (or did some division by 0) which caused the solver to crash. Have you done a sensitivity check on the mesh? How many elements does it have? What is the Courant number for your simulation? Best regards |
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June 27, 2012, 08:51 |
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#24 |
Member
Join Date: Dec 2009
Posts: 44
Rep Power: 16 |
Are you running in parallel? I have seen this behaviour occcasionally from parallel runs of the CFX-Solver, in that the real problem is disguised, and associated messages are not output.
If you can run it in serial, and there is a problem with the setup, then the solver should write some messages which are more useful than just 'error code 255'. CG |
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June 27, 2012, 23:34 |
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#25 | |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
Quote:
I run it in serial. But if it was something with my setup,is it related to my inlet(I set it 0MPa) or outlet(20MPa)? After reading the CFX-help file ,it is recommended that inlet:0MPa,outlet:2.667kg/s according to the real situation.But it still can't be right |
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July 1, 2012, 22:19 |
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#26 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
Hi,guys. I forgot the mesh statitics in CFX-SOLVER when the solver failed to solve the simulation. So is it for sure that the failure is caused by coarse mesh?
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July 1, 2012, 22:28 |
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#27 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
the picture I copied from CFX-solver
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July 1, 2012, 22:30 |
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#28 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
And some other pictures
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July 2, 2012, 09:36 |
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#29 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144 |
The average density of your fluid is 9e-7. Are you sure this is correct?
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July 2, 2012, 10:04 |
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#30 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
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July 2, 2012, 13:17 |
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#31 |
Member
Luis Filipe Fabiani
Join Date: Apr 2009
Posts: 43
Rep Power: 17 |
Well, given that water has a density of about 1.000 kg/m3 at room temperature and it is incompresible, 9e-7 sure means something is wrong.
What are the Inlet conditions?? In CFD-Post plot some variables (temperature, velocities, etc) to check if the problem is on a specific area of your domain. |
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July 2, 2012, 19:57 |
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#32 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144 |
I suspect that you are using 0 reference pressure and almost zero inlet/outlet pressure, leading to very low density fluid as the pressure is just about absolute zero. The reference pressure needs to be set at a suitable level for the simulation - if this thing is close to atmospheric pressure then use 1 [atm] for the reference pressure.
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July 2, 2012, 23:42 |
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#33 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
Follows are my further information in my cfx-pre
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July 2, 2012, 23:43 |
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#34 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
And these pictures.
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July 2, 2012, 23:50 |
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#35 | |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
Quote:
As to the density of fluid,is the pre-setting I have finished is wrong or the cfx-solver itself? |
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July 2, 2012, 23:51 |
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#36 | |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
Quote:
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July 3, 2012, 15:28 |
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#37 |
Member
Luis Filipe Fabiani
Join Date: Apr 2009
Posts: 43
Rep Power: 17 |
Correct me if I am wrong, but it does not seem that the gears are turning. How can there be a flow if the gears are not turning?
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July 3, 2012, 20:09 |
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#38 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144 |
I see your inlet and outlet are both 20MPa, and your reference pressure is 1atm. In that case you should use a reference pressure of 20.1MPa and an inlet and outlet pressure of 0 Pa.
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July 4, 2012, 00:49 |
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#39 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
The gear1 and gear2 are turning around their geometric centers respectively. the angular velocity both are 2000r/min,u can check that.
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July 4, 2012, 00:53 |
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#40 |
Member
Stefan
Join Date: May 2012
Posts: 49
Rep Power: 14 |
Thanks. there are 3 boundaries: inlet,outlet,inletsmall(you can check the first picture attached under the thread).the inlet:2.37m/s;outlet(opening) 20MPa;inletsmall(close to the outlet;set as opening )20MPa.The inletsmall I have modified ,not as OUTLET type
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