Fast monotonically integrated large eddy simulation solver: validation of a new scalable tool to study and optimize indoor ventilation

Niklaus Leuenberger, Rui Yang, Lukas Münzel, Roberto Verzicco, Detlef Lohse, Lydia Bourouiba, Patrick Jenny

Abstract:

Indoor ventilation is underutilized for the control of exposure to infectious pathogens. Occupancy restrictions
during the pandemic showed the acute need to control detailed airflow patterns, particularly in heavily occupied
spaces, such as lecture halls or offices, and not just to focus on air changes. Displacement ventilation is increasingly
considered a viable energy efficient approach. However, control of airflow patterns from displacement ventilation
requires us to understand them first. The challenge in doing so is that, on the one hand, detailed numerical
simulations – such as direct numerical simulations (DNSs) – enable the most accurate assessment of the flow,
but they are computationally prohibitively costly, thus impractical. On the other hand, large eddy simulations
(LES) use parametrizations instead of explicitly capturing small-scale flow processes critical to capturing the
inhomogeneous mixing and fluid–boundary interactions. Moreover, their use for generalizable insights requires
extensive validation against experiments or already validated gold-standard DNSs. In this study, we start to address
this challenge by employing efficient monotonically integrated LES (MILES) to simulate airflows in large-scale
geometries and benchmark against relevant gold-standard DNSs. We discuss the validity and limitations of MILES.
Via its application to a lecture hall, we showcase its emerging potential as an assessment tool for indoor air mixing
heterogeneity.