Multi Component Mixing Boundary Conditions

[tmoser]

I'm trying to work through one of the CFA advanced tutorials for multi-component mixing on a model of a mixing nozzle and I'm having trouble with defining the boundary conditions. The tutorial is telling me to first define the total flow as a Specified Volumetric Flux and then define the components as a Specified Value. It appears to me that the Specified Values are a percent of the Specified Volumetric Flux. (See the attached Multicomp_dir) Makes sense to me. The problem is that the Program doesn't work this way. When I set the mixture to Specified Volumetric Flux the program doesn't let you select Specified Value for the components, it only allows Specified Volumetric Flux. (See Multicomp_CFA) So what am I supposed to do? Calculate and enter the Volumetric Flux of each componet at the various boundaries?

Also, on the Nozzle_Side_Inlet I expected the Specified Values for the components to add up to 1.0 but they don't. The tutorial says 0.99 for O2 and 0.9 for H2O. Is this a typo?

FWIW, I'm using Creo 7.0 for the tutorial.

I'm wondering if the tutorial was written for an earlier version of Creo/CFA and the program changed but the tutorial didn't. This makes learning very difficult.

https://support.ptc.com/help/creo/creo_pma/r6.0/usascii/index.html#page/tutorials_pma%2FMulMix_AssigningBoundaryConditions.html%23

[VladimirN]

 Hi,

Please also send your question here as well: documentation@ptc.com

[cfdgeek · Accepted solution]

Hello, 

This tutorial has some issues. First flow module should be added. That is the major thing cause the BC issue. You should see something in the attached figure after adding flow module.

Then you found the other typo, it should be 0.99 for o2 and 0.01 for h20. 

[tmoser]

Thank you, that was very helpful and I was able to run the model. However, my results don't match what the tutorial is showing. I double checked my entries and experimented with some different values but I still don't match. At least it's running.

I wonder if there are still some typo's in the specified values. 

[cfdgeek]

Thanks. I ask my colleagues to double check it. Here is the following items he found. Could you please check item 3 and test it again? Those will be fixed for this tutorial. 

1. The names of two boundaries while renaming were flipped. BC2 should be renamed to Nozzle_Inlet and BC3 should be renamed to Nozzle_Side_Inlet. But in the manual it was mentioned in the other way.

2. As you mentioned, addition of flow and turbulence modules was not mentioned in the Online manual. But it exists in our internal CFA manual.

3. The boundary condition for O2 concentration at the Nozzle_Side_Inlet was incorrect in the Online manual. I verified in the CFA and SimericsMP manuals that O2 concentration should be 0.1 and H20 concentration should be 0.9.

[tmoser]

We're making progress. I think I had already caught the name swap. The side inlet is on the side.  🐵

Another question though. Why does the tutorial have us set H20 to Ideal Gas Law? It doesn't seem like the temperatures are high enough for it to be steam.