How to resolve cfx error 123
 

Hi
I getting the message
Ansys cfx solver exited with return code 123

Pl See the attachment...n reply your sggestions

In your case, the absolute pressure is out of bounds, i.e. less than 0.

You should review your boundary conditions setup, and reference pressure for consistency. Otherwise, the solver is not able to maintain the absolute pressure within bounds based while trying to converge the solution.

Is your setup a steady state analysis ? Perhaps reducing the timestep ? or is the mesh resolution enough, or too coarse ?

Thank you for your reply
Its a steady state analysis..mesh is fine...Why cant i use mass flow rate as inlet conditions and supersonic at outlet...

Defining Domains in CFX
 

Hi
I am doing a conjugate heat transfer..Flow along with solid..two fow are seperated by solid...In one fluid domain reaction takes place and in other only coolant

How to define coolant as it is not taking part in reactions..whether coolant has to be mentioned as seperate domain...Say it is H2-O2 reaction and coolant is Liquid H2...

Hoping for your suggestions
Regards

As opaque said, the error in because the simulation resulted in negative absolute pressure. So you need to find what caused the negative absolute pressure to occur. This is often boundary condition choice. What boundary conditions have you imposed?

I am doing heat transfer in C-D nozzle..Conditions: Inlet mass flow and outlet supersonic...And am giving rotational periodicity(in domain interfaces) for each sides as i have modelled only a sector of 60deg..

Also if i am using a rotational periodicity for the sides in Domain interfaces...At inlet whether i have to give total flow rate or flow rate corresponding to that sector only...

You specify the flow rate for the segment you have modelled only.

Are you sure your boundary conditions are valid? If your outlet is pulling harder than your inlet can supply gas then you will get a negative absolute pressure.

Your simulation has progressed quite a way before crashing. So rerun it and output a backup file just before it crashes. Then you should be able to see where the region of low pressure is and that should help debug it.

Thanks for you peoples suggestions..I have set pr as inlet condition and supersonic at outlet..now works fine...

Now two flows are seperated by solid...In one reaction takes place(fuel n oxi) and in other only coolant

How to define coolant as it is not taking part in reactions..whether coolant has to be mentioned as seperate domain...Say it is (gaseous H2- O2) reaction and coolant is Liquid H2...

Pls look in to my prob

If you disable the "constant domain physics" option then you should be able to have one domain a single phase single component flow and the other domain multiphase/multicomponent.

Thank you..i could do different domains with that..

I have modelled only sector of 60 deg of the C-D nozzle...If i am giving both the sides 'rotational periodicity' in 'domain interfaces' OR if i am giving 'symmetry' in 'boundary conditions' for the sides...
1. What is the physical difference and which one is correct for my problem...Rotational periodicity or symmetry
2. Since am using 60 deg..whether symmetry conditions on sides is valid
3. Pls explain the "symmetry" and "rotational periodicity" difference?
Pls comment on my problem

You should read the documentation and a CFD textbook on this. You really need to understand the basics to set up a good CFD simulation.

Symmetry implies no flow normal to the boundary and zero normal gradient for all variables.

Periodicity implies that the values at one side of the interface get mapped to the equivalent location on the other side of the interface.

Hi
Got a warning when i opened my result file...Did nt understood..Pls help
WARNING
Object(s) 'Domain 1 Default' referenced in object 'EXPORT/Location List' either do not exist or are currently unavailable for use. During state load this could be because the referenced object(s) have yet to be fully initialized.

Where can i find the documentation

Look under help.

Got it...When i do conjugate heat transfer (fluid domain where combustion occurs and solid domain of 1.2 mm thick simulating chamber) the results doesnt shows any temp variation in the solid outer wall..??
Conditions given were
1. fluid -solid domain interface - general connection
2. Heat transfer- Thermal energy for solid domain
3. No boundary conditions on solid domain..only initial temp ~ ambient 300K

Is there anything i am missing....Conduction has to takeplace right?

Gone thru documentation...but as you can see very little they mentioned abt this

Suggestions pls...(My actual objective is to know the coolant temp variation along the CD nozzle ...that is two fluid domains and in between the solid domain)

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

The fuel and oxi enters thru different paths n comes in contact only in chamber
Inlet - pressure and flow normal to boundary, Outlet - supersonic
sides- symmetry

Fluid - reacting mixture
reaction -h2 -o2 single step, eddy dissipation and finite rate chemistry
stoitiometry - H2-1 and O2 -0.5

SOLVER
upwind
RMS - E-4

I have put the model n the result shows low temp in chamber?? why??

You have not provided much information so I cannot say anything for certain.

Your minimum temperature is 88K. That's pretty cold. Are you sure that is correct? If the starting temperature is way too cold that might explain why the flame never gets too hot.

What else inf is needed..can u specify..
Lower temp is 88K ...But the comb of H2-O2 should provide higher temp rt?

I just want you to confirm that 88K is reasonable for a minimum temperature. It is very low and most people would not be modelling stuff at that temperature.

Please show a cross section of your mesh and your CCL file.

Now the prob solved when i corrected my mesh...Now when am running i am getting an error msg which says
The non-dimensional near wall temperature (T+) has been clipped |
| for calculation of Wall Heat Transfer Coefficient. |
| |
| Boundary Condition : ch innershell Side 1 2 |
| T+ clip value = 1.0000E-10 |
| |
| If this situation persists and you are using the High Speed Model, |
| consider enabling Mach number based blending between low speed and |
| high speed wall functions. You can do so by specifying a Mach |
| number threshold as follows: |
| |
| EXPERT PARAMETERS: |
| highspeed wf mach threshold = 0.1 # default=0.0 (off) |
| END

I have added this expert parameter but it is giving a global warning that

In Analysis 'Flow Analysis 1': One or more expert parameters have been enabled. Note that expert parameters are intended for use only by customers who are experienced in the use of CFX, or who have been instructed to use them by ANSYS Customer Support. Use of the parameters is not fully supported, and may have unexpected or unintended consequences both for the quality of results and the performance of the CFX-Solver.

So how to add this expert parameter

that is not an error but just a warning. it appears when you enable any expert parameter (even quite simple one like relaxation term).
If you know what you are doing you can ignore it, if not be quite prudent and look for documentation.

but what i am using is not there in default parameters so i edited the CCL file.. ....When i process the CCL it doesnt show any error...but when solver starts running it shows that it cannot include the expert parameter

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| Errors were encountered in the CFX Command Language for this run: |
| |
| Error: Sub-object 'EXPERT PARAMETERS' is not allowed in / |
+--------------------------------------------------------------------+

have you done the change on CFX-pre or CFX Solver directly ?

sorry for delayed reply...i have done in cfx pre

well, i don't know what happend...
maybe the implementation of a new parameter only with CCL is quite bad
you can always try to add another expert parameter (like under-relaxation term) and see if the CCL is still good.

ok..now for the time being i am running without editing the CCL...how to tackle the error i am getting

Parallel run: Received message from slave
-----------------------------------------
Slave partition : 9
Slave routine : ErrAction
Master location : RCVBUF,MSGTAG=1016
Message label : 001100279
Message follows below - :

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Floating point exception: Overflow |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

Parallel run: Received message from slave
-----------------------------------------
Slave partition : 9
Slave routine : ErrAction
Master location : RCVBUF,MSGTAG=1016
Message label : 001100279
Message follows below - :

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine FPX: C_FPX_HANDLER |
| |
| |
| |
| |
| |

FAQ: http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F

Thank you. i will go through it

When i go thru u r link, in FSI portion it is mentioned that fluid - solid interaction has to be done seperatly. Fluid in CFX-Pre and solid in Work bench and club together...Is it ncessary ? I can do it in CFX-Pre itself rt by defining different domains and club by domain interface (Fluid -solid)??

hi
i want to know in particle distribution..what do you mean by rossin ramler size and power
if my SMD is 200...how to specify the above two parameters...

Hi
I need a simple help..i want to give that Hydrogen Cp (specific heat at const pr) varies with temp as i am using it as a coolant...How to give that or how to input

Then make the Hydrogen Cp a function of temperature using a CEL expression or a 1D interpolation function.

Thank you..How to create shared library. I have written my fortran code and saved as filename.F...Now the documentation says the following...


A script called cfx5mkext is used to create shared libraries. You can run cfx5mkext -help for information on the arguments accepted by the script. To create the shared libraries execute:

cfx5mkext myroutine1.F


where to run ???? In which command line ???

Plssss help..

creating shared library
 

Pls see my last post on may 19

Error
 

ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Floating point exception: Zero divide |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine FPX: C_FPX_HANDLER |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

+--------------------------------------------------------------------+
| An error has occurred in cfx5solve: |
| |
| The ANSYS CFX solver exited with return code 1. No results file |
| has been created. |
+--------------------------------------------------------------------+

I am getting this error at accumulated time step(doing a steady state combustion) where i asked to backup the results...When i gave at interval 10..error occurred after writing the backup results...When i gave 20s interval to backup result..error message occured at 20...Why?

Hoping for your help