[a.m.]

Hello All,

I try to model CH4 combustion and I'd like to make mesh adaption in the reaction region. Hence, I set up CH4.Mass Fraction as adaption criteria in CFX12 Pre. Mesh Adaption was started every 10 iterations.
While solver was running, Refiner has started and terminated with the message:

"An error has occurred in cfx5solve:

The ANSYS CFX mesh refiner could not be started, or exited with return code 255:"

Before that one I've recived a windows send report message about refiner.

What does code 255 means?
When it usually appears?

Regards, A.m.

[zxin]

what i can tell you is, last time I encountered this error code is because of large aspect ratio which exceeded the limit.

Hope this would help..

[a.m.]

Thanks zxin,

I've solved this problem by mesh changing. First time I used ANSYS Meshing to generate mesh. I checked its quality in ICEM CFD and received following results: min = 0.013, max = 23.05, mean = 1.87 (aspect ratio).
Then I generated ICEM CFD mesh and checked it. I received following:
min = 0.25, max = 0.99, mean = 0.75 (aspect ratio). Also I decreased a numer of elements by a factor of 1.8 and removed prism layers (inflantion).
With the new mesh remesher works perfectly.

P.S.
old mesh

new mesh

[zxin]

That's great...
but sometimes, my mesh with aspect ratio close to 1000 generated by Ansys Mesh, works fine with CFX, CFX is quite stable solver, i think...

[ghorrocks]

But with no prism layers your boundary layer modelling will be hopeless. You clearly have a mesh quality problem, but you need to generate a high quality mesh with prism layers.

[a.m.]

I' m modeling the CH4 combustion process, therefore finer stoichiometric region is more important for me then boundary layer.

[ghorrocks]

Isn't the heat transfer important? Won't that set the heat lost to the walls, and be a major contributor to combustion temperature? You will need a good prism layer mesh to resolve that.

[a.m.]

Thanks ghorrocks,

Sure it is very important too and I'm working on it By the way, how many prism layers I need to resolve the wall heat transfer?

[ghorrocks]

That's problem dependent. The discussion in the CFX documentation on near-wall modelling is a good starting point, but you then need to do a sensitivity study to find out what your specific case requires.

[a.m.]

Thanks a lot!

[OffshoreStructuralEnginer]

I do not know what Error code 255 means. Im not an expert at Ansys or CFD. But I do know that it has been solved, every single time, by deleting my mesh and remeshing with new settings. I am not saying you should do this. If you are truly desperate you may give it a try.

[vmlxb6]

What kind of meshing is advisable to solve the ERROR code 255 ???

I am using ICEM CFD to mesh my geometry. Am ugetting the following error
"The ANSYS CFX solver could not be started, or exited with return |
| code 255: . No results file has been created."

Now am using the following:

Mesh type on surface: All Tri
Mesh type in volume: Tetra/Mixed
surface Mesh method: Patch Independent
volume Mesh method: Robust (octree)

Thank you very much