Ultra-Clean-Air (UCA) operating theatres aim to minimise surgical instrument contamination and wound infection through high flow rates of ultra-clean air, reducing the presence of Microbe Carrying Particles (MCPs). This study investigates the airflow patterns and ventilation characteristics of a UCA operating theatre (OT) under standard ventilation system operating conditions, considering both empty and partially occupied scenarios. Utilising a precise computational model, quasi-Direct Numerical Simulations (qDNS) were conducted to delineate flow velocity profiles, energy spectra, distributions of turbulent kinetic energy, energy dissipation rate, local Kolmogorov scales, and pressure-based coherent structures. These results were also complemented by a tracer gas decay analysis following ASHRAE standard guidelines. Simulations showed that contrary to the intended laminar regime, the OT’s geometry inherently fosters a predominantly turbulent airflow, sustained until evacuation through the exhaust vents, and facilitating recirculation zones irrespective of occupancy level. Notably, the occupied scenario demonstrated superior ventilation efficiency, a phenomenon attributed to enhanced kinetic energy induced by the additional obstructions. The findings underscore the critical role of UCA-OT design in mitigating MCP dissemination, highlighting the potential to augment the design to optimise airflow across a broader theatre spectrum, thereby diminishing recirculation zones and consequently reducing the propensity for Surgical Site Infections (SSIs). The study advocates for design refinements to harness the turbulent dynamics beneficially, steering towards a safer surgical environment.

The use of a synthetic jet as the flow control technique to modulate a turbulent incompressible round jet was explored and assessed by numerical simulations. The flow response was characterised in terms of turbulent statistics and acoustic response in the far-field. A quasi-Direct Numerical Simulation (qDNS) strategy was used to predict the turbulent effects. The Ffowcs-Williams and Hawkings (FWH) acoustic analogy was employed to compute the far-field acoustic response. An amplification effect of the instabilities induced by the control jet was observed for some of the parameters explored. It was observed that the control technique allows controlling the axial distribution of the production and dissipation of turbulent kinetic energy, but with respect to the acoustic aspects, the appearance of a greater number of noise sources was observed, which in the far-field, resulted in an increase from 1 to 20 dB of the equivalent noise for the different operating parameters of the control technique studied.

A Reynolds average Navier Stokes (RANS) modeling approach is employed in the description of the single-phase turbulent fluid dynamics in a pipe equipped with Kenics static elements (KSEs). The uncertainties related to the domain discretization are quantified to allow a robust validation of the computational model with experiments. The local flow fields and the pressure drop as predicted by different turbulence models adopted in the literature are compared with purposely collected particle image velocimetry and pressure transducer data. The computational model is employed for studying the local fluid dynamics produced by different configurations of the KSEs, in terms of mean and turbulent flow variables, and mean age of the flow. The results are discussed from the perspective of a carbon mineralization process run in a proposed novel reactor configuration, where phenomena such as the multiphase fluid dynamics and interphase mass transfer are fundamental. The computational model identified for the simulation of such system is based on the transient solution of the RANS equations with the k−ω SST (shear stress transport) turbulence model. The alternating Kenics configuration can be employed to enhance the turbulent dissipation rate, and therefore, the bubble breakup and interphase mass transfer coefficient. On the contrary, the configuration with KSEs in the same orientation can be exploited for inline gas separation due to the strong angular accelerations, producing phase segregation based on the density difference between the phases. Indeed, this work lays the foundations to extend the computational approach to multiphase gas–liquid simulations.