[Bill_Yang]

Hello, everyone,

Could you help me with this issue?

I am starting to use the JL 4 steps gas reaction mechanism for coal combustion. So I need to use the EDC model. I have met some converge problems. My problems are listed as follows:
a) Previously, I used the EDM. Everything (the flame, the converge, etc) is OK for my case.
b) Since EDM is regarded to overestimate the gas reaction and ignore the dissociation, I start to use the JL-4 steps mechanism for my coal air and oxy combustion.
c) When I start to test the EDC for the case of coal air combustion, the fluent runs not correctly. The flame and the converge is really bad.
d) my calculation procedures are like this for the edc case: i)first calculate a cold flow case ii) setting up the finite-rate/eddy-dissipation and using the same reactions of the JL-4 steps mechanism (reverse reaction is ignored in fr/edm) through importing the chemkin.chem file iii) after setting up the fr/edm, then I start the ignition. iv) running for several thousand steps;v) then change to edc and also active the reverse reactions in the JL-4steps mechanism.
e) Then I get the error message from fluent after some iterations: "dasac failure at Temperature = 1283.92 K: Continuing.." In addition, the furnace temperature is quite low (<1000 K) start from the fr/edm stage, which should not be correct.

Could anyone help with this?

Many thanks.