[p.galimutti]

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

[monkey1]

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.

[lffabiani]

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

[cfdgremlin]

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

[shanxuewenjdx]

Originally Posted by cfdgremlin

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

many thanks!
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

[shanxuewenjdx]

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?

[shanxuewenjdx]

the picture I copied from CFX-solver

[shanxuewenjdx]

And some other pictures

[ghorrocks]

The average density of your fluid is 9e-7. Are you sure this is correct?

[shanxuewenjdx]

Originally Posted by ghorrocks

The average density of your fluid is 9e-7. Are you sure this is correct?

I chose water as fluid material.anything wrong?

[lffabiani]

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.

[ghorrocks]

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.

[shanxuewenjdx]

Follows are my further information in my cfx-pre

[shanxuewenjdx]

And these pictures.

[shanxuewenjdx]

Originally Posted by lffabiani

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.

Thanks a lot. For more information, u can see more pictures above.the Inlet:2.37m/s.
As to the density of fluid,is the pre-setting I have finished is wrong or the cfx-solver itself?

[shanxuewenjdx]

Originally Posted by ghorrocks

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.

So kind you are. u can check further information from the above pictures.

[lffabiani]

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?

[ghorrocks]

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.

[shanxuewenjdx]

Originally Posted by lffabiani

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?

The gear1 and gear2 are turning around their geometric centers respectively. the angular velocity both are 2000r/min,u can check that.

[shanxuewenjdx]

Originally Posted by ghorrocks

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.

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