Help needed for turbulent Combustion Modelling. The solution always diverges within 10 iterations. This happenes only for enthalpy calculations. Can you help me what is the bug? and where to rectify it?

sincerely sudeep

Do you have Chemico turned on as an option for Enthalpy?

Chinor

Yes, I have chemico-Thermal switched ON for enthalpy. Do you think there could be any unit inconsistency in the code/ or at the user interface?

Hi Try to write down some more information. Something like what models you use. Otherwise it is quite difficult to say what is wrong. It could be some wrong setting, it could be just not suitable underrelaxation.

Try the calculation as a cold run, and restart from it. try to have this calculation with a scalar which "carry" the fuel. If it does not help, try manual setting for initial field - rise the temperature.

Use just upwind differencing, try strong underelaxation.

good luck

Matej

Just give us a brief describtion of your geometry, what kind of combustion model, do you have a moving mesh? what is the time step length?e.t.c

Im using premixed with eddy break up model. I am using a user subroutine for N2. It is a one step CH4+2O2->2H2O+CO2 Im solving CH4,O2,H2O and CO2 as "Transport" (i dont know what exactly it means by transport) and N2 by user sub routine (which is nothing but 1- (sum(rest of scalars)). I want to initialize the field with 0.23 of O2 and 0.77 N2. The option doesnot work! Please advice me on how can i get the correct initialization. I gave "STOP" command at the user subroutine and It looks as though it doesnt stop! May be it doesnt take the user-subroutine! Then, why that option????