Open Access

ARTICLE

Ventilation Velocity vs. Airborne Infection Risk: A Combined CFD and Field Study of CO₂ and Viral Aerosols

Chuhan Zhao^1,*, Souad Morsli², Laurent Caramelle³, Mohammed El Ganaoui³

1 Faculty of Sciences and Technologies, University of Lorraine, Nancy, 54000, France
2 Laboratory for the Study of Microstructures and Mechanics of Materials (LEM3), École Nationale des Ingénieurs de Metz (ENIM), University of Lorraine, Metz, 57070, France
3 Laboratory for Studies and Research on Wood Materials (LERMAB), Institut Henri Poincaré de Longwy (IUT), University of Lorraine, Longwy, 54400, France

* Corresponding Author: Chuhan Zhao. Email:

(This article belongs to the Special Issue: Materials and Energy an Updated Image for 2023)

Fluid Dynamics & Materials Processing 2025, 21(8), 2001-2025. https://doi.org/10.32604/fdmp.2025.068093

Received 21 May 2025; Accepted 22 August 2025; Issue published 12 September 2025

Abstract

Carbon dioxide (CO₂) is often monitored as a convenient yardstick for indoor air safety, yet its ability to stand in for pathogen-laden aerosols has never been settled. To probe the question, we reproduced an open-plan office at full scale (7.2 m 5.2 m 2.8 m) and introduced a breathing plume that carried 4% CO₂, together with a polydisperse aerosol spanning 0.5–10 m (1320 particles s⁻¹). Inlet air was supplied at 0.7, 1.4, and 2.1 m s⁻¹, and the resulting fields were simulated with a Realisable – RANS model coupled to Lagrangian particle tracking. Nine strategically placed probes provided validation; the calibrated solution deviated from the experiment by 58 ppm for CO₂ (8.1% RMSE) and 0.008 m s⁻¹ for velocity (15.7% RMSE). Despite this agreement, gas and particles behaved in sharply different ways. Room-averaged CO₂ varied by <15%, whereas the aerosol mass rose to almost three-fold the background within slow-moving corner vortices. Sub-micron particles stayed aloft along streamlines, while those 5 m peeled away and settled on nearby surfaces. The divergence shows that neither the CO₂ level nor the mean age of air, taken in isolation, delineates all high-exposure zones. We therefore recommend that ventilation design be informed by a composite diagnosis that couples gas data, size-resolved particle measurements, and rapid CFD appraisal.

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