Fluids

Fluids

Limitations of Species modeling via UDFs

    • GeoDesy
      Subscriber

      Greetings all,


      I am trying to model a jet flame using the GRI-3.0 mechanism which contains 53 species in conjuction with a SLW UDF for the calculation of the absorption coefficient. 


      For the simulations I am using Fluent 19.2.


      The UDF works for mechanisms with a lower number of species, however when I try to add the GRI-3.0 mechanism I get the following error:


      Received signal SIGIOT.


      and on the Linux terminal I get:


      *** stack smashing detected ***


      The UDF works by defining user-defined-gray-bands. I also tried to use Fluent 15 and I get the 50 species limitation error message.


      As far as I understand this error causes fluent to abort due to wrong memory allocations. 


      So I was wondering, is the calculation of user-defined-gray-bands still capped at 50 species?  And if it is, is there any solution to my problem?

    • Rob
      Ansys Employee

      Not sure, but I don't tend to model combustion systems. If you alter the mechanism to 49 species does it work?

    • GeoDesy
      Subscriber

      I did use a different mechanism GRI-2.11 with 49 species while using the exact same code and it works. I also reduced the GRI-3.0 and using the same code it works.

    • Rob
      Ansys Employee

      Then there must be a limit. I'll query on our side as it may be an oversight when some of the other limits were lifted. 

    • GeoDesy
      Subscriber

      So is there any update on the query on your side? 

    • Rob
      Ansys Employee

      Species should be fine, there may be a limit on the grey bands. 

    • GeoDesy
      Subscriber

      I tried runs with 1,2,5 and 10 bands and I still get the same error. When I do the same with 36, 49 and 50 species the simulations proceed like they should. 


      So is there any way to circumvent this limit?

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