[kola77]

Hello everybody,
I am trying to conduct a simulation of a simple shell-tube heat exchanger, but as soon as I start the run the solver crashes with an error with the following explanation:

If the isolated regions do not have the pressure level set either by the boundary conditions or using a reference pressure equation, you may encounter severe robustness problems.

This situation may have arisen because a domain interface was not properly defined during problem setup. Please carefully check the setup.

The solver will stop now and write a results file. The isolated regions can be visualised in CFX Post by making plots of the variable "Isolated Volumes".

If you are sure that the pressure level is set in each isolated fluid region then you can force the solver to turn off this check by setting the expert parameter "check isolated regions = f".

+--------------------------------------------------------------------+ | An error has occurred in cfx5solve: | | | | The ANSYS CFX solver exited with return code 1. | +--------------------------------------------------------------------+

End of solution stage.

I know this usually has something to do with problems of the geometry/mesh, but I couldn't find any noticeable glitches in mine. There were also no unconnected regions, the the interfaces seem to be correct. Nevertheless, what I have tried is the following:

• I have carefully and several times reviewed my setup
• I have redesigned my model from scratch
• I have refined the mesh
• I have tried to simulate a single pipe inside of a shell

All of the above ended with the same error, yet when I start an old file of another heat exchanger I have simulated a while ago it works fine. I have carefully examined my setup of that one and I can't fine any differences in the setup. If anybody has ANY idea what might be causing this I would be the happiest man on earth, since I am slowly getting desperate.

Is it possible that my installation of ANSYS is damaged in some way?

Thank you in advance for any potential help!

[ghorrocks]

The error message tells you exactly what the problem is. If you have two or more fluid regions which are not connected then you need to set a pressure value in each of them. So the easiest way is to make sure each fluid region has a pressure inlet or outlet.

[kola77]

That's the problem. There are no regions which wouldn't have a boundary condition set. All of them are set to inlet/outlet, wall or interface. The reference pressure is set in each of them. I have tried several configurations, but still the solver keeps crashing.

Would you please be kind enough and take a couple of minutes to check my setup? I'm sure it's some newbie mistake that can be easily recognized. If so, it's here: http://www.megaupload.com/?d=N33WZTOW

[Sanyo]

Hi,

As Glenn said, its definitely problem of isolated fluid regions. Its because of unconnected regions. Sometimes duplicate/multiple faces remain unattended. Hence one or more fluid regions remain unconnected/ isolated. Please check the faces joining the regions. If faces are not connected, you could see the nonconformal mesh or multiple faces at same location.

You may also carry out one solution with the expert parameter "check isolated regions = f". This would enable you to understand the problem region.

Hope this helps.

Regards,

-Sanyo

[ghorrocks]

All of them are set to inlet/outlet, wall or interface.

That is not what I said. A velocity inlet and a mass flow outlet has not defined the pressure. One of the inlet and outlets in each region needs to be a pressure boundary to set the pressure.

[kola77]

All of the outlets had a pressure defined.

Anyway, I have managed to get it running, after changing the geometry a bit so i only had one outlet/inlet that splits into 13 later and not several regions defined as either one of them. After doing this it worked without a problem. Thank you for your help guys, much appreciated! Cheers!

[mohw2002]

HI FOR EVERY ONE
PLEASE I WORK ON MY GEOMETRY PIPE WITH ONE PERFORATION AND I MESH IT BY HEXA NOT TETRA BECAUSE I WANT TO CALCULATE WALL SHEAR STRESS BECAUSE HEXA GIVE US SMOOTH LINE WHEN WE ARE DRAWING THE BEHAVIOR OF WALL SHEAR AND PRESSURE DROP. WHEN I SENT THE MESH TO CFX IT CANNOT DID THE RESOLVING BECAUSE THE ERROR IS COMING AS BELOW HOW CAN I TREAT THIS PROBLEM. THE SIDE PLANE I PUT IT AFTER ONCE THE ERROR APPEAR. tHE SIDE PLANE IT IS VERTICAL AXIS FOR THE SIDE OF THE PIPE BECAUSE I DRAW HALF PIPE.


ERROR #002100013 has occurred in subroutine Chk_Splane. |
| Message: |
| The symmetry boundary condition requires that the boundary patch |
| mesh faces form a plane or axis. However, face set 6 in the |
| symmetry boundary patch |
| |
| SIDE PLANE |
| |
| is not in a strict plane, which means that at least one of its |
| faces is not parallel to the others. To make the solver run |
| you can do one of the following: |
| |
| (1) Make sure that this symmetry boundary patch is in a plane or |
| axis by checking and regenerating the mesh. |
| (2) If the symmetry boundary patch is an axis rather than a |
| plane, change the tolerance of the degeneracy check by |
| increasing the value of the Solver Expert Parameter |
| 'degeneracy check tolerance' (the default value is 1.e-4). |
| (3) Increase the value of the Solver Expert Parameter |
| 'vector parallel tolerance' (the default value is 1 deg.). |
| Note that the accuracy of the symmetry condition may decrease |
| as the tolerance is increased. This is because the tolerance |
| is the number of degrees that a mesh face normal is allowed |
| to deviate from the average normal for the entire face set.

[Sanyo]

Dear mohw2002,

It is a problem with symmetry boundary condition. Instead using symmetry, try using wall type BC with free slip.

Regards,

-Sanyo

[mohw2002]

Originally Posted by Sanyo

Dear mohw2002,

It is a problem with symmetry boundary condition. Instead using symmetry, try using wall type BC with free slip.

Regards,

-Sanyo

thanks for reply
I solved this problem because I made a mistake at ICEM CFD, I chose axis after did the mesh I was trying to solve it but without any success. I returned to ICEM CFD and delete the mesh and rearrange the parts.
Thanks
I have a diffucelet when I mesh by hexa do you have simple procedure or good tutorials?

Regards

[susilo]

If the isolated regions do not have the pressure level set either by the boundary conditions or using a reference pressure equation, you may encounter severe robustness problems.

This situation may have arisen because a domain interface was not properly defined during problem setup. Please carefully check the setup.

The solver will stop now and write a results file. The isolated regions can be visualised in CFX Post by making plots of the variable "Isolated Volumes".

If you are sure that the pressure level is set in each isolated fluid region then you can force the solver to turn off this check by setting the expert parameter "check isolated regions = f".

+--------------------------------------------------------------------+ | An error has occurred in cfx5solve: | | | | The ANSYS CFX solver exited with return code 1. | +--------------------------------------------------------------------+

End of solution stage.

[shelkeprithvi]

I am also having same problem with my geometry. In pre-CFX when I am giving symmetry as boundary condition at the mid section of the pipe those red arrows are surrounding only three sides of the green rectangle shown in the pictures attached. Can anyone tell me why I am getting this type of error.

[ghorrocks]

You mean you are getting the isolated regions/pressure level is not set error? Isn't it obvious? Then you need to set a pressure level.

[Sanyo]

Prithvi,

Be specific please. It is not clear whether you have an issue of arrows showing in 3 directions only or your solver exited with returned code 1.

If you are asking of arrows, it might be just a representation & actually solver has considered symmetry correctly. Have your solve crashed? If yes try to check physics setup. Give more details.

Regards,

Sanyo

[umar afzal]

Originally Posted by ghorrocks

The error message tells you exactly what the problem is. If you have two or more fluid regions which are not connected then you need to set a pressure value in each of them. So the easiest way is to make sure each fluid region has a pressure inlet or outlet.

hi
please tell me what does it mean?
The ANSYS CFX solver exited with return code 1. No results file has been
created.
when add more nodes and i want use slover it couldnt run just show me abut line . is there have any problem in my BC ? or factor effect ??please

[ghorrocks]

Please read the error message carefully. The error code does not tell you much, there is no list of definitions for error codes that I am aware of (so I do not know why ANSYS put it in there....). All the information is in the error text.

Your simulation needs the pressure set somewhere. This could be by a boundary condition, an initial condition or some other function. But it needs to be set somehow. Either you did not set any pressure condition or the condition you set is not valid.

[umar afzal]

hi everyone i hope all of you fine and happy with good health
i have problem during the cfx solver using the problem is that


The ANSYS CFX solver exited with return code 1. No results file has been
created.
when i want to run the solver give me above wearing and i spend much time to solve it by ,y self but still cant any one tell me please how to solve this kind for problem ???is there have any problem in BC ??or nodes

[ghorrocks]

Did you read my previous post? I have already answered your question.

[umar afzal]

Originally Posted by ghorrocks

Did you read my previous post? I have already answered your question.

yeas i read it thank you so much ...

[umar afzal]

Originally Posted by ghorrocks

Please read the error message carefully. The error code does not tell you much, there is no list of definitions for error codes that I am aware of (so I do not know why ANSYS put it in there....). All the information is in the error text.

Your simulation needs the pressure set somewhere. This could be by a boundary condition, an initial condition or some other function. But it needs to be set somehow. Either you did not set any pressure condition or the condition you set is not valid.

i set pressure on the outlet surface and temp used for inlet i and heat flux on the all heated wall .. is there have any other place to need pressure please i mean with out outlet.....

[ghorrocks]

Please post an image of what you are modelling and your output file.