modeling of coupled problem
Dear all,
I am going to model a catalytic combustion process, which is used to burn off the trace amount of fugitive ethane. The case description are as below: (1) I have to use a hot gases from exsting burners , to raise the temp of my process, I planned to use a configuration like a double pipe heat exchanger, but the gases to be burnt will be entering from the side ^ ^   burnt gases out                                                    <  gases to be burnt         ^  hot gases My problem is how can I couple the two flow in order to run the calc. , and how could I specify the heat transfer from the hot gases to the cold stream. I expect your suggestion/experience/thought to direct my modeling of this combustion process. I appreciate your time and expertise. Godfrey 
Re: modeling of coupled problem
I suggest this method.
(1) Set the momentum and energy boundary conditions and turn off the "energy" equation in "solve>control". (2) Solve each flow field separately in a same geometry. An approach to solve this problem is to set one flow field as a solid part and solve the other field. Then export solved flow field data by the function "interpolate" in a Fluent solver. Thus, you can solve the other flow filed in a same manner.(change the solid type continuum and fluid type continuum) (3) Couple two flow field data in a same geometry and turn off the "flow" equation and turn on the "energy" equation in "solve>control". Then solve energy equation only. P.S. Above method is valid when there is no natural convection and flow field variables(velocity components) are not governed by temperature. 
Re: modeling of coupled problem
In this case there is natural convection on outer fluid side as well as the temperature is very influential in flow field..
Godfrey 
Re: modeling of coupled problem
Well, how about using "Profile file" in solver? Boundary condition at interface between two regions could be set after solving hot fluid region. Thus you can, I believe, solve the natural convection problem caused by hot fluid region which is spacially separated with cold fluid region.

Re: modeling of coupled problem
Ok I will try this..
but could I use the inner wall as inteface where I can define my boundary condition or I should defined the new interface boundary condition..?? thanx for help 
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