Learning Forum

[Sahiti]

Hello all..

I'm using Ansys Workbench 18.1 with solver as Fluent. The module is PEMFC and electrolysis. I'm trying to validate my experimental results of PEM Water electrolysis cell. I keep getting this error " received a fatal signal ( Segmentation Fault )". After the error, the solver says calculation complete. But the solution cell is giving error "An error occured in FLUENT while reading the data file". I don't understand why that is happening. 

I tried with different geometries, changing the mesh and gave edge sizing and resetting the setup. I am not using any UDF also. I even tried updating the drivers of my computer. I'm not able to narrow down the issue. Can someone help me please?

[Rob]

Start with a simple model (ie without species, heat transfer or chemistry) and see what happens. Then gradually make it more complicated: turning everything on at once makes it both easy to make a mistake and hard to spot where the error is. 

I'd also advise updating to 2019R2. 

[Sahiti]

Sir,

I tried with turning off the all you suggested. After giving the boundary conditions, I checked in the check case under run calculations. There are no recommendations under mesh. Under solver, there is a recommendation to change the method from first order upwind to second order upwind. Nothing else has come up. Still the Segmentation error is coming. Anything else you would suggest where I can check?

Also in student version 2019R2, the error is, f1 process cannot be started.

[Rob]

No, turn everything off and then try to initialise & run. Turn models on until it fails.  The case check just looks at the case but will allow (for example) a velocity of 1,000,000,000 m/s which will cause solver problems. 

[Sahiti]

Sir..

I did what you said and it did help there is progress and the calculations ran. But after turning on reaction heating along with joule heating, error came saying "Divergence detected in AMG solver:species-2". Does that mean there is something wrong with the boundary condition or solver settings or methods? I thought meshing is fine because the result came fine with only joule heating and without any models on.

[Rob]

It could also be the amount & gradient of flow/energy/species caused by the addition of an extra species. How does the result look for species but no reactions?

[Sahiti]

Although the results are coming as all zeros. And since it is a pressure based solver, I gave coupled as the scheme.

 iter continuity x-velocity y-velocity z-velocity energy h2 o2 h2o time/iter

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

1 1.0000e+00 1.0694e-01 6.8032e-01 2.7301e-01 6.1577e-05 0.0000e+00 0.0000e+00 1.0968e-03 14:25 11

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

2 5.0254e-01 4.2611e-02 2.6969e-01 1.1184e-01 6.1576e-06 0.0000e+00 0.0000e+00 1.5916e-04 1:45:48 10

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

3 5.4952e-01 1.4838e-02 9.3327e-02 4.1194e-02 5.8241e-06 0.0000e+00 0.0000e+00 1.9846e-05 1:43:43 9

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

4 4.8809e-01 5.4416e-03 3.3916e-02 1.6428e-02 4.4131e-06 0.0000e+00 0.0000e+00 1.9593e-06 2:04:04 8

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

5 4.4043e-01 2.2429e-03 1.3895e-02 7.5334e-03 3.1086e-06 0.0000e+00 0.0000e+00 3.8737e-07 1:50:53 7

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

6 3.6388e-01 9.8660e-04 6.0966e-03 3.8253e-03 2.5961e-06 0.0000e+00 0.0000e+00 5.7646e-08 15:47 6

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

7 2.9197e-01 4.5746e-04 2.8008e-03 2.1242e-03 2.2485e-06 0.0000e+00 0.0000e+00 1.3447e-08 1:22:49 5

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

8 2.3146e-01 2.2200e-04 1.3429e-03 1.2774e-03 1.9475e-06 0.0000e+00 0.0000e+00 2.6475e-09 1:13:24 4

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

9 1.9078e-01 1.1619e-04 6.8909e-04 8.3613e-04 1.7111e-06 0.0000e+00 0.0000e+00 8.7927e-10 0:57:40 3

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

10 1.5773e-01 6.5009e-05 3.8236e-04 5.9442e-04 1.4538e-06 0.0000e+00 0.0000e+00 2.7333e-10 08:46 2

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

11 1.3302e-01 3.9987e-05 2.3731e-04 4.4544e-04 1.1698e-06 0.0000e+00 0.0000e+00 7.8202e-11 0:192 1

V_cell = 0.750000 (V) ... V_open = 1.100000 (V)

I_anode = 0.000000 (A/cm^2) ... I_cathode = 0.000000 (A/cm^2) ... dI_mea = 0.000000 (A/cm^2) ... dI_stk = 0.000000 (A/cm^2)

iter continuity x-velocity y-velocity z-velocity energy h2 o2 h2o time/iter

12 1.1546e-01 2.7643e-05 1.6233e-04 3.4015e-04 9.6947e-07 0.0000e+00 0.0000e+00 2.6455e-11 0:00:00 0

Registering Udflib, ()

Writing data to PEMWEfinaltrial2edit_if_needed_filesdp0FFFFluentFFF.1.ip ...

x-coord

y-coord

z-coord

pressure

x-velocity

y-velocity

z-velocity

temperature

species-3

species-2

species-1

species-0

uds-0

uds-1

uds-2

uds-3

hyb_init-0

hyb_init-1

Done.

 

 

Calculation complete.

[Rob]

OK, so now turn on the next bit and work through. 

[Sahiti]

I reduced the number of elements to 7200. Now the divergence issue is not coming anymore. But the values of anode current densities are all coming to zero.

[Rob]

Which suggests that you've missed a setting?  Work through the model carefully and check each step. 

[Sahiti]

Thank you sir..It's working fine now.