Hi,

I have to use a pressure-outlet boundary at a flue exit in my model, but I do not know species mass fractions at this boundary.

Can I leave these values blank or are values needed?

Regards,

Eric

Hi,

Yes they are needed because you may have reverse flow across the boundary and these values will then be used. If you do not have the data as I expect you don't then give a good guess as to what you feel the likely species distribution will be. As you run the calculation, you will then have to do a manual iteration and alter them as required.

Hope this helps

Thank you for your reply Tom,

Does this mean that mass fraction boundary conditions applied, in the pressure outlet panel, at the flue exit are only used by fluent if there is reversed flow at the exit?

If so, does this mean that I could use the mass fraction values from a simulation that was conducted under different conditions but on the same model?

Thanks,

Eric

Yes - These values are only used if there is reverse flow otherwise only data from inside the domain shall be used.

You could use previous data from another simulation. You will see the species mass fractions if there is reverse flow. If you got reverse flow on a previous simluation it is likely to occur agian. Try and put in a species distribition as close as possible to what you think it should be. You can then judge for yourself by looking at some contour plots of each species.

Good luck.