6th November 2014

Abercus presents at the FLACS user group meeting in London

The FLACS user group (FLUG) meeting was hosted by BP at the Sunbury facility south of London. Abercus' contribution considered how to model the local ventilation efficiency for a facility in accordance with the ISO15138 (2007) requirements.

Calculation of the global ventilation efficiency is fairly intuitive since it considers ventilation exchanges across surfaces bounding the region of interest. And even if a region is well-ventilated in a global sense, there may be zones of recirculation within that are less well ventilated in the local sense.

Abercus presented a comparison of two alternative methods for calculating the local ventilation efficiency using the FLACS CFD code, one transient method and the other a steady-state method. The two methods are commonly assumed to provide equivalent predictions but this presentation demonstrated that whilst they generally predict similar qualitative behaviour for many ventilation patterns, they can predict very different quantitative behaviour.

Whilst the use of the steady-state method may be attractive in terms of reduced computational effort, the ISO15138 standard requires the use of the transient method. Since FLACS is a transient CFD code, the ISO15138 methodology is well suited to a solution strategy with FLACS as the CFD code.