Fluent returned reaction rates and that calculated using CFF

- February 17, 2021 at 1:23 pm
  
  scholar
  Subscriber
  
  Hello everyone,nI am using Fluent 2020R1 for modeling the gasification process. I am using the laminar model for homogenous reaction, where the information of activation energy, Arrhenius rate constant, temperature exponent, reactants, and products stoichiometric coefficients information is given as input.nThe fluent returned rate (only homogenous reaction) and that calculated using custom field function do not match. nThere is two orders of magnitude of difference between the rates. On the other hand, the hand-calculated rate (using excel) by using the concentration returned by fluent and that calculated using CFF matches very well.nDid anyone face such an issue? Where the rates do not match with the one calculated using CFF or UDF? Or am I missing something here?nAny suggestion will be of great help.nThank youn
- February 17, 2021 at 4:00 pm
  
  Rob
  Ansys Employee
  
  Are you out by exactly two orders of magnitude? n
- February 17, 2021 at 4:20 pm
  
  scholar
  Subscriber
  
  Hi Rob,nThere is a difference in values as well. nThe excel file with detailed calculation is enclosed which has the information of hand-calculated, cff, and fluent returned rates.nn
- February 18, 2021 at 5:19 pm
  
  Rob
  Ansys Employee
  
  I'm not allowed to open that: check the rules section on here. nIf you're seeing a real difference you then need to work through the maths and definitions of the macros and terms in the CFF, UDF etc. Everything should check out, so it's likely a maths error. Remember that UDFs use SI units regardless of what you're using in the model. n
- February 27, 2021 at 10:50 am
  
  scholar
  Subscriber
  
  Hi Rob,nI set last species as N2. Now the rates are matching.nThank you for your suggestions and time.n

Viewing 4 reply threads

You must be logged in to reply to this topic.

Ansys Innovation Space

Boost Ansys Fluent Simulations with AWS

Computational Fluid Dynamics (CFD) helps engineers design products in which the flow of fluid components is a significant challenge. These different use cases often require large complex models to solve on a traditional workstation. Click here to join this event to learn how to leverage Ansys Fluids on the cloud, thanks to Ansys Gateway powered by AWS.

Earth Rescue – An Ansys Online Series

The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.

Ansys Blog

Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.

Trending discussions