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November 30, 2017, 01:12 |
error in simulaton
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#1 |
Member
gasem
Join Date: Jul 2017
Posts: 51
Rep Power: 8 |
hi everybody
i see this error in my simulation what is the meaning of it? and how i can solve this error [CVODES ERROR] CVode At t = 2.47902e-006, mxstep steps taken before reaching tout. and this warning WARNING ... extrapolating on the temperature calculation get_temp_from_sensible_sie problem found in rank 0 at cell 12827, located at <0.00321319, -0.00147355, -0.00592695>, in region 0, whose level=9, ii=206, jj=251, kk=392 And this error:something is wrong in function get_tem_from_table_masfraction:upper_energy_value must be greater tan lower_energy_value Last edited by jiliyur; December 2, 2017 at 12:16. |
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December 2, 2017, 03:07 |
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#2 |
Member
gasem
Join Date: Jul 2017
Posts: 51
Rep Power: 8 |
no any one help me please
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December 5, 2017, 14:16 |
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#3 | |
Senior Member
Nitesh Attal
Join Date: Sep 2017
Location: Convergent Science, Northville MI
Posts: 113
Rep Power: 8 |
Quote:
With limited information above it is very difficult to identify what went wrong. Can you elaborate on what you are simulating? What is in the vicinity of the location x = 0.00321319 y=-0.00147355 and z=-0.00592695? CVODES error is related to solution of combustion ODES, please check your combustion model settings. Finally if nothing stands out please share your case with support@convergecfd.com Thanks, |
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December 6, 2017, 23:29 |
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#4 |
Member
gasem
Join Date: Jul 2017
Posts: 51
Rep Power: 8 |
Hi thanks for your reply i simulation pcci biodiesel engine but when i simulation my pressure diagram is very fine but my emission is very bad for this issue i select Schmidt numbur 0.1 until decrease emission and this error has seen why does my emission is too much?i simulation sector geometry and use example case of converge
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December 7, 2017, 13:55 |
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#5 | |
Senior Member
Nitesh Attal
Join Date: Sep 2017
Location: Convergent Science, Northville MI
Posts: 113
Rep Power: 8 |
Quote:
Typically value of Sc is between 0.7-0.9 (default 0.78) but you have reduced this significantly. The enhanced mass diffusion resulting from small Sc might nonphysically boosting the non-premix combustion. Did you get the CVODES error when you were using the default Sc (0.78)? Thanks, |
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December 8, 2017, 03:01 |
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#6 |
Member
gasem
Join Date: Jul 2017
Posts: 51
Rep Power: 8 |
Hi i simulate experimental data from this work "A Comprehensive Combustion Model for
Biodiesel-Fueled Engine Simulations ; Jessica Brakora; doi:10.4271/2013-01-1099" and i compare CO emission . I ensert the same initial condition of this work but does it differ from sector simulation compare with nonsector simulation? If yes how can i insert this data correctly. No there isnt this error in .78 Schmidt number but when i decrease it emission decrease and this error seen . i insert 7 type of fuel according below picture .my simulation is premixed charge compression ignition but the example case is non premixed . is these different? Last edited by jiliyur; December 8, 2017 at 04:08. |
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December 8, 2017, 11:36 |
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#7 | |
Senior Member
Nitesh Attal
Join Date: Sep 2017
Location: Convergent Science, Northville MI
Posts: 113
Rep Power: 8 |
Quote:
Engine sector is a closed cycle simulation. The initial conditions should correspond to the time (usually few crank angles after IVC) you are starting the simulation. The initial conditions in the paper (for full engine simulation?) might not correspond to the start time of your engine sector case (hence IC might differ so please check if the start time/crank). Ideally you would want to run the full engine simulation until IVC and use a map file at IVC to initialize the sector case (For details please look at the user manual and introductory training slides available to download from www.convergecfd.com/downloads). No error at Sc=0.78 is a good sign. Do you have the correct (or same as the paper you compare to) reaction mechanism? |
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December 9, 2017, 02:23 |
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#8 |
Member
gasem
Join Date: Jul 2017
Posts: 51
Rep Power: 8 |
Hi how can i make sure i assumed a periodic flow field?this initial conditions are for sector simulation in paper . I use the same as paper reaction mechanism . This mechanism has used in several works successfully at least insofar i know.can i use the initial conditions that achieves from above explanation? in paper there are some initial conditions like pressure and temperature and EGR but tke and eps there arent i think the turbolens is not enough for this reason CO emission is too much but i can solve this problem how do you think ?
Last edited by jiliyur; December 9, 2017 at 15:46. |
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December 11, 2017, 14:43 |
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#9 | |
Senior Member
Nitesh Attal
Join Date: Sep 2017
Location: Convergent Science, Northville MI
Posts: 113
Rep Power: 8 |
Quote:
Thanks, |
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December 12, 2017, 04:29 |
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#10 |
Member
gasem
Join Date: Jul 2017
Posts: 51
Rep Power: 8 |
Thank you very much i am going sent it for you with jiliyur@yahoo.com email i say this to know me
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