Please HELP (Smoke simulation)

Amr

Hi everyone,

I am simulating a 2D smoke event in a simplified atrium as rectangular room with two openings in cieling (one vent and one exhaust fan) and an inlet air opening on one side wall. The rest sides "edges" are modelled as wall. Smoke is modelled as "Mass and energy source" mixture of CO2 and CO without using a combustion model. Now I need guidance in the following issues:

1- As for the smoke modeling, if I wanted to model O2 depletion due to combustion, could I put an O2 sink in the same fluid zone that I put a CO, CO2 sources in? How?

2-As for Boundaries, I have set the inlet air space as Pressure inlet, the exhaust opening as Exhaust Fan and the vent opening as outlet vent. Is this correct?. Any ideas from your previous work?. I got repeatedly a stiff converged solutions and velocity contours are unrealistic.

3-When setting boundaries, in the exhaust fan BC, a species fraction is requested. Now, since the species fraction is one variable that I need to know after simulation, how does Fluent request its value before hand?. Is there a way to force Fluent to calculate the species fraction at Exhaust fan or Outlet vent BC?

Would appreciate your help so much. Thanks for your time.

Amr