Heterogenous reaction rates returned by Fluent and CFD-POST are different

- July 28, 2021 at 7:02 pm
  
  scholar
  Subscriber
  
  The distribution of the heterogeneous reaction rates in Fluent and CFD-POST are very different (see Figure 1). The units for heterogenous reaction rate in CFD-POST are in mol/m3s. Even if it is converted to kmol/m3s (0.001 х mol/m3s ), the magnitude will be much less than what Fluent is giving. Also, the volume integral of heterogeneous reaction rates written in output file (using “Solution-Report Definitions”) of Fluent and that calculated using CFD-POST are matching. The same is the case for all the heterogenous reaction rates.
  Also, I stored the heterogenous reaction rate (included using UDF) in UDMI. The value returned by UDMI and that showed in CFD-POST are the same.
  Did anyone face this issue in which the distribution of the heterogeneous reaction rates are different in Fluent and CFD-POST?
- July 28, 2021 at 11:12 pm
  
  scholar
  Subscriber
  
  This issue is present when I run simulations on HPC. In my local machine, this issue is not there. The Fluent version I use on HPC is same as local machine (Fluent 2020R1)
- August 2, 2021 at 4:24 pm
  
  Surya Deb
  Ansys Employee
  
  Hello,
  Do you read the Fluent results in CFD post and observe this difference?
  How do the other variables like velocity, pressure behave? Do they compare with Fluent results?
  Also, Fluent results on HPC match the Fluent results on your local system?
  Regards SD
- August 2, 2021 at 6:19 pm
  
  scholar
  Subscriber
  
  Hi Yes, the distribution of heterogeneous reaction rate in Fluent and that shown in CFD-POST are different.
  The other variables like velocity, pressure, mole fraction of species, homogenous reaction rates in Fluent and CFD-POST are the same.
  Also in Figure 1 (a), the heterogeneous reaction rate (C+02-->CO2) is also present near the coal inlet (the side injection). Whereas, in CFD-POST the rate is completely zero near coal inlet, which should not be the case. Now I have another doubt. Which heterogeneous reaction rate is correct ? or which rate is actually going into Fluent code of species transport and other conservation equations? The one shown in Fluent or CFD-POST? How to cross-check this?
  The heterogeneous reaction rates are implemented in Fluent using UDF. Is there any other way to implement heterogenous reactions in Fluent?