Fluids

Fluids

Pre-processing Langmuir-Hinshelwood mechanism file in Chemkin

    • Biborka Boga
      Subscriber

      Hi!
      I am trying to perform the pre-processing of a LH mechanism file in Chemkin.

      First, when I am performing the preprocessing in Chemkin for the reaction without considering the LH parameters, everything is fine.
      As soon as I am specifying the LH parameters, the following error appears:

       1. A+B=>C+D+E+F       3.15E-03    0.0        0.0
            Error...3rd-body requires (+M) in reaction...LANG/A 1 0.0 0.0 0.95/
      !! ERROR IN DATA STATEMENT NUMBER  1
      SYNTAX ERROR, OR ILLEGAL VALUE
            Error...unrecognized 3rd-body species...LANG
            Error...problem finding 3rd-body parameter...LANG/A 1 0.0 0.0 0.95/
      !! ERROR IN DATA STATEMENT NUMBER  1
      SYNTAX ERROR, OR ILLEGAL VALUE
            Error...unrecognized 3rd-body species...LANG
            Error...problem finding 3rd-body parameter...LANG/O2 1 0.0 0.0 0.05/
            Error...unrecognized 3rd-body species...LHDE

      P.S. For simplicity I have replaced the reactants and products with A, B, C...

      Can you please offer me some hints how can I overcome these errors? I do not really have any idea about the menaing of 3rd body specie.
      Thank you very much in advance!

    • Judy Cooper
      Ansys Employee

      Hi Biborka:

      A lot of the errors are correct for the defiiencies in the mechanism.  The LH format has specific requirements.  For instance, for a reaction with 3rd bodies, the reaction must be of the form:

      A+B+M=>AB 

      where M is a wildcard that represents the 3rd body.  

      M is an unspecified collision partner that carries away excess energy to stabilize the  molecule (forward direction) or supplies energy to break the bond (reverse direction). 

      The format required by LH is documented in the Chemkin Help Documentation -Chemkin Input Manual, which has a section for Gas Phase Chemistry.

      I hope this helps.

       

    • Biborka Boga
      Subscriber

      Thank you very much your feedback! I will try again to import the mechanism considering your suggestions. 

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