## 3 Materials and Methods
### Model Validation  
#### 3.4.1 Description of Physical Experiments  
Before starting the numerical analysis, the numerical model should be verified and compared with a similar application. In this study, two physical experiments were selected from the literature to validate the CFD model before applying it to the current research. The first is the small-scale empty chamber experiment that was conducted by [PERSON] et al. (2006) [35], whereas the second experiment is the bioaerosol deposition experiment that was performed by [PERSON] et al. (2013) [27]. These two experiments are characterized by the availability of both airflow velocity measurements and the particle concentration profiles data.  
In the following paragraphs, a brief description of the two physical experiments for model validation is presented.  
First validation experiment  
This experiment was conducted for a small-scale empty chamber. The chamber was prismatic in shape with dimensions of 0.8 m in length, 0.4 m in width, and 0.4 m in height. The inlet and outlet notches of the airflow and airborne particles were 0.04 by 0.04 m, and they were located concentric with the longitudinal vertical center plane (Y = 0.2 m) as shown in Figure 1. The isothermal chamber was ventilated using an axial fan situated at the inlet where the airborne particles were also injected using a solid particle dispenser with injected particles of a mean particle size of 10 \(\upmu\)m. The inlet air velocity was equal to 0.225 m/s, which corresponds to a ventilation rate of 10 air change cycles per hour (ACH).  
The spatial variation of the air velocity and the particle concentration profiles (within the center plane) were measured using a phase Doppler anemometer.  
\begin{table}
\begin{tabular}{c c c} \hline
**Item** & **Description** & **Selection** \\ \hline Software & CFD Package & Fluent-Workbench 18.2 \\ \hline \multirow{4}{*}{Numerical Settings} & Turbulence Model & k-\(\epsilon\) (RNG) model \\ \cline{2-3}  & Turbulent kinetics, momentum and rate of turbulent dissipation & Second order Upwinding scheme \\ \cline{2-3}  & Gradient for Upwinding & Green-Gauss Node-based Scheme \\ \cline{2-3}  & Pressure-Velocity Coupling Scheme & Simple-C \\ \hline Meshing & Cell Shape & Tetrahedral \\ \hline \multirow{4}{*}{Boundary Conditions} & Inlet & Velocity-inlet \\ \cline{2-3}  & Outlet & Pressure-Outlet \\ \cline{2-3}  & Wall & Standard log-law \\ \hline \multirow{4}{*}{Computing Resources} & Processing speed & 3.1 GHz \\ \cline{2-3}  & No of used Cores & 32 \\ \cline{1-1} \cline{2-3}  & No of used Core-hours & 600 \\ \hline \end{tabular}
\end{table}
Table 1: Characteristics of the CFD Model.  
2. Second validation experiment  
The second experiment focused on studying the spatial deposition of aerosolized _Staphylococcus aureus_ in an aerobiology empty room. The room dimensions were 4.26 m \(\times\) 3.36 m \(\times\) 2.26 m with insulated walls, and the room was supplied by a HEPA filtered air through a high-level wall-mounted diffuser. The room geometry and the locations of the velocity measuring poles are shown in Figure 2a. 2.5 m bioaerosol particles from a pre-autoclaved six-jet collision nebulizer were injected at the room's geometric center, and the deposition was measured using groups of five 90 mm Petri dishes (settle plates) located around specified locations on the floor surface in the room, Figure 2b. The fractional bacteria count Ci representing the normalized deposition distributions at each collection point was used to compare the experimental measurements and the CFD results.