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Old   November 30, 2017, 02:12
Default error in simulaton
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gasem
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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 13:16.
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Old   December 2, 2017, 04:07
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no any one help me please
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Old   December 5, 2017, 15:16
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Quote:
Originally Posted by jiliyur View Post
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
Hello,

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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Old   December 7, 2017, 00:29
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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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Old   December 7, 2017, 14:55
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Quote:
Originally Posted by jiliyur View Post
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
What are you comparing the results with (experiment or another simulation)? Also what quantity you are comparing (NOx?, Soot, HC?)? How are you ensuring that the initial conditions are consistent for the sector simulation?

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)?

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Old   December 8, 2017, 04:01
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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?
Attached Images
File Type: jpg 1.jpg (113.0 KB, 8 views)
File Type: jpg 2.jpg (91.6 KB, 6 views)

Last edited by jiliyur; December 8, 2017 at 05:08.
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Old   December 8, 2017, 12:36
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Quote:
Originally Posted by jiliyur View Post
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?
I do not have access to the above referenced paper also please make sure you can assume a periodic flow field (low tumble and high swirl) before performing an engine sector calculation.
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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Old   December 9, 2017, 03:23
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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 16:46.
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Old   December 11, 2017, 15:43
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Quote:
Originally Posted by jiliyur View Post
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 ?
As the paper presents results from sector simulation, periodicity is assumed (and valid). If you are using the same initial conditions, CONVERGE results should be consistent with the paper. Please send your case setup to support@convergecfd.com and we will help you resolve this issue.

Thanks,
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Old   December 12, 2017, 05:29
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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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