[prashant79_ss]

Hi,
I am working on electric motor CHT analysis with source terms in stator and rotor components. I have setup CFD case with mass flow as inlet and static pressure as outlet and good fluid-solid interfaces with 37 million cells.
after setting CFD case and solution diverges every time reaching at 10 iterations, so in order to avoid solution diverging for complex geometry with heat transfer, I had followed with simpler approach,
- first case: Running with cold flow run with energy equation switched off with rotor components were set with rotational speed.
- second case : energy equation is switched on with initialized condition( cold flow used) and it runs fine and converging. Here I had set with no body motion of rotor components ( i.e. no angular speed).
- Now, I have set rotor components with angular speeds with initialized solution of previous (i.e second run result) run, it runs for 10 iterations with H-energy and T-energy unable to stabilize and finally diverges with following error,
ERROR #004100018 has occurred in subroutine FINMES. | | Message: | | Fatal overflow in linear solver.
anybody have any ideas on why error comes out after I set rotational speed in rotor components with energy eqn solving ? I don't see this error when I run with cold flow run.

[ghorrocks]

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

Which version of CFX are you using? Which interface model are you using for the rotating domain (frozen rotor, transient rotor/stator)?

[Martin_Sz]

which method do You use for rotor?
Do You define this rotor like solid body or immersed solid?
If solid body try immersed
Best regards

[billy7590]

Hi,
I am facing the same problem in my simulation of centrifugal pump. I am modeling the impeller and the inlet pipe. I have added a monitor point at the outlet of impeller. When simulating, after the first few time steps, pressure at outlet starts reaching unrealistic values e.g. -2e+9 and so on. Then the error comes saying FATAL OVERFLOW IN LINEAR SOLVER.
I am using total pressure inlet BC at the pipe inlet and mass flow rate BC at the outlet of impeller, and frozen rotor interface. Any ideas what could be the reason for the fatal overflow?

[jp_]

As per Ghorrock's post above, have you tried reducing the timestep? Is the mass flow in enough?

[billy7590]

I reduced the time step and it worked fine.
Thanks alot