Combustion in a cavity
 

Hi there!

I am trying to model combustion reaction between methane and oxygen in a t-shape cavity geometry.

I managed to implement combustion reactions at different conditions and in different geometries using the reactingFoam solver. All of those simulations were given inlet patches that contained the reactants (CH4, O2) and were transported to one another by specifying velocity at those same inlet patches. A good example of such simulation is the reacting elbow tutorial (https://bit.ly/2KVEiKv)

Now, I am trying to calculate the time it would take to "flush out" oxygen from a cavity by reacting it with methane (see attached file) - the main problem is how to specify a certain height (h in the pic) if you may of that Oxygen i.e. specify initial volume. --- so the difference from above is that my "inlet patch" of O2 would have moved some height before CH4 is introduced into the system.

Please advise on how to go on to implement that.
Thank you!