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cfd guy June 18, 2002 18:03

How EDM model works in CFX-5?
Hi everybody,
I want to make a simple test with the EDM combustion model in CFX-5. My reacting fluid is Hydrogen Air (H2, O2, N2 and H2O). I've defined N2 as the constraint equation. I have several inlets and I've set the following mass fractions: 0.21 for O2, H2 = H2O = 0. In just one inlet I've set 1. for H2 and 0. for the other species. I'm not using any radiation model.
First I've solved the turbulent flow and then I switched off the fluids and tke and epsilon equations. After a few iterations of the energy and mass fractions equations I've noted no presence of the H2O in my solution and no change in the temperature field, ie. no reaction. What did I forget to set? I tested both Bulk Viscosity and Kinematic Viscosity. My initial conditions for the flow are a cold flow converged solution and for the species are "Automatic with Value" : H2 = H2O = 0. ; O2 = 0.21
Thanks in advance, cfd guy

Neale June 19, 2002 18:33

Re: How EDM model works in CFX-5?
Make sure you have some initial products in the domain. So, try reinitialising the H2O mass fraction to a non-zero value, say 0.01 or something and rerun it.

Set the H2O mass fraction to "Value" in the CCL to do this, rather than "Automatic with Value".


cfd guy June 20, 2002 11:35

Re: How EDM model works in CFX-5?
Thanks Neale,
But I found that the simplest way is to start from the scratch solving all equations together and the combustion effects will appear naturally. However, someone told me that is possible to trick the code and start a combustion problem from a cold solution modifying a simple coefficient in the EDM model.
Regards, cfd guy

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