reaction two parallel pipes

alp

hi there,

I simulate in a cylindrical pipe methane total oxidation (exothermic) and iso-octane steam reforming (endothermic), respectively to observe temperature and product composition changes through the pipe and I get very good results from the simulations.

after these steps, I want to observe heat transfer between two parallel pipe. In one of that oxidation and in other one reforming takes place. for this aim, rectangular prism was created in gambit and two identical cylinders were placed in it. the problem is that "I want to enter two different operating conditions for each cylinder. for one of those 2.9 atm and for the other one 1 atm how can I do that in FLUENT".

when I enter the average of these two, FLUENT does not converge and I encounter temperature limited and back flow warnings.which type of outflow conditions could I use? please help me

thanks in advance