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Simulation of DMFC in fluent

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Old   March 21, 2011, 23:01
Default Simulation of DMFC in fluent
  #1
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Qingqing Hu
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Hello, everyone! I have a problem in my subject, I need to simulate the working conditions of DMFC(or even special-shaped DMFC),but I have never done that, and there is no people know how to finish it, so I would like to search for help from someone with experiences. Thank you!

Some days ago I tried to finish an example from others, but when iterating errors appeared such as:
iter continuity x-velocity y-velocity z-velocity energy h2 o2 h2o uds-0 uds-1 uds-3 time/iter
V_cell = 0.750000 (V) ... V_open = 0.950000 (V)
I_anode = 0.037519 (A/cm^2) ... I_cathode = 0.037519 (A/cm^2) ... dI_mea = -0.000000 (A/cm^2) ... dI_stk = -0.000000 (A/cm^2)
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
1 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 0.0000e+00 16:25:03 199
V_cell = 0.750000 (V) ... V_open = 0.950000 (V)
I_anode = 1.#QNAN0 (A/cm^2) ... I_cathode = 1.#QNAN0 (A/cm^2) ... dI_mea = 1.#QNAN0 (A/cm^2) ... dI_stk = 1.#QNAN0 (A/cm^2)
reversed flow in 100 faces on pressure-outlet 19.
reversed flow in 100 faces on pressure-outlet 20.

I don't know what is the reason, is there anyone knows? Please tell me what should I do to avoid such errors.
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Old   August 26, 2011, 13:08
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BIAO YU
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Hi hqqicedream, have you solved the problems? I'm also working on DMFC modeling with CFD and I encountered similar problems DMFC UDF problems. If you have some ideas, could you help me? Thanks!


Quote:
Originally Posted by hqqicedream View Post
Hello, everyone! I have a problem in my subject, I need to simulate the working conditions of DMFC(or even special-shaped DMFC),but I have never done that, and there is no people know how to finish it, so I would like to search for help from someone with experiences. Thank you!

Some days ago I tried to finish an example from others, but when iterating errors appeared such as:
iter continuity x-velocity y-velocity z-velocity energy h2 o2 h2o uds-0 uds-1 uds-3 time/iter
V_cell = 0.750000 (V) ... V_open = 0.950000 (V)
I_anode = 0.037519 (A/cm^2) ... I_cathode = 0.037519 (A/cm^2) ... dI_mea = -0.000000 (A/cm^2) ... dI_stk = -0.000000 (A/cm^2)
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
1 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 0.0000e+00 16:25:03 199
V_cell = 0.750000 (V) ... V_open = 0.950000 (V)
I_anode = 1.#QNAN0 (A/cm^2) ... I_cathode = 1.#QNAN0 (A/cm^2) ... dI_mea = 1.#QNAN0 (A/cm^2) ... dI_stk = 1.#QNAN0 (A/cm^2)
reversed flow in 100 faces on pressure-outlet 19.
reversed flow in 100 faces on pressure-outlet 20.

I don't know what is the reason, is there anyone knows? Please tell me what should I do to avoid such errors.
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Old   April 5, 2012, 01:57
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  #3
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WU Fei
Join Date: Mar 2012
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Quote:
Originally Posted by hqqicedream View Post
Hello, everyone! I have a problem in my subject, I need to simulate the working conditions of DMFC(or even special-shaped DMFC),but I have never done that, and there is no people know how to finish it, so I would like to search for help from someone with experiences. Thank you!

Some days ago I tried to finish an example from others, but when iterating errors appeared such as:
iter continuity x-velocity y-velocity z-velocity energy h2 o2 h2o uds-0 uds-1 uds-3 time/iter
V_cell = 0.750000 (V) ... V_open = 0.950000 (V)
I_anode = 0.037519 (A/cm^2) ... I_cathode = 0.037519 (A/cm^2) ... dI_mea = -0.000000 (A/cm^2) ... dI_stk = -0.000000 (A/cm^2)
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
Error: Floating point error: invalid number
Error Object: ()
1 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 1.#QNBe+00 0.0000e+00 16:25:03 199
V_cell = 0.750000 (V) ... V_open = 0.950000 (V)
I_anode = 1.#QNAN0 (A/cm^2) ... I_cathode = 1.#QNAN0 (A/cm^2) ... dI_mea = 1.#QNAN0 (A/cm^2) ... dI_stk = 1.#QNAN0 (A/cm^2)
reversed flow in 100 faces on pressure-outlet 19.
reversed flow in 100 faces on pressure-outlet 20.

I don't know what is the reason, is there anyone knows? Please tell me what should I do to avoid such errors.

hi i work on PEMFC, which is similar with yours, previously i encountered with that problem too, sometimes i decrease under relaxation restart calculation again the problem seems disappered, wish this could help/


i wonder how did you mesh catalyst layer and membrane in gambit, i find it is hard to mesh these super thin layer, and i encounter with many problem too, no one can enlighten me , poor
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