Smoke shaft

[ShehabGamrah]

I noticed when modelling a full smoke shaft to full height with a exhaust surface at the head and a hole opening into the corridor compared to an exhaust surface opening into corridor as a representation of the shaft, the full height model outperforms in smoke clearance yet both are assigned same flow rate. So wanted to check if this is expected, and due to what theory?

[drjfloyd]

The flow field is not going to be the same between the two. If your exhaust vent is on the wall in the corridor, you have unidirectional, constant flow over that vent. With the vent at the top of the shaft and an opening in the wall, that opening will now have time and spatially varying flow. You should look at the flow rates and velocity fields for the two simulations and determine what is happening in your specific simulations.

[ShehabGamrah]

In both cases the flow exhaust is set to the same speed. Regardless of the position of the vent shouldn’t the volume of smoke exhausted be the same, also the flow rate at the hole in the corridor when a full shaft is modelled is equal to the when just a vent is applied. Moreover, the flow rate is constant across the shaft.

[drjfloyd]

You are extracting at different locations. The flow field is not the same. Look at the flow, temperature, and smoke fields in the two simulations so that you can understand what is happening.