[myeandel]

Hi All,

I'm unable to upload any files due to the simulations being on a work computer that cant be accessed so I'll have to describe my issue.

I am having trouble selecting the correct outlet boundary conditions for a non reacting multi-species flow using rhoReactingBuoyantFoam. Unfortunately there is no tutorial for this solver and other buoyant solvers do not have similar pressure outlets for me to base my choices on.

I have tried out various settings that seemed to be appropriate with no luck, currently my p, prgh and U files are as set up as follows;

p

internalField - uniform 1e5

inlet - zeroGradient

outlet - fixedValue - uniform 1e5

wall - zeroGradient

frontBack - empty

prgh

internalField - uniform 1e5

inlet - zeroGradient

outlet - fixedValue - uniform 1e5

wall - zeroGradient

frontBack - empty

U

internalField - uniform (0 0 0)

inlet - flowRateInletVelocity - massFlowRate 0.00005

outlet - pressureInletOutletVelocity - uniform (0 0 0)

wall - zeroGradient

frontBack - empty

The initial species for the internal domain is 0.77N2 + 0.23O2 and the inlet is 0.11H2 + 0.89O2.

This results in an internal domain with a top to bottom smooth pressure difference of 20pa over 2m, however at the outlet there is no gradient. I am aware that fixedFluxPressure is supposed to be used for buoyancy cases but this causes flow into the domain from the outlet and the pressure the rise significantly.

Any explanation on what I have done wrong or missed would be very appreciated.

Thanks,
Mat

[danobis]

Hello myeandel,


did you solve your issues?
I think I am facing something similar: I am currently using reactingFoam (no chemistry, no combustion) to simulate gas dispersion in air, but something should be wrong with my BCs because I get recirculation at the outlet.

Let me know if you have any tips.
Daniele