## 3 Results and Discussion
### Numerical Results  
The numerical model reproduced the entire experimental chamber with the general ventilation system. Figure 17 presents the distributions of velocity and temperature inside the modeled domain in the case without a PV diffuser in different vertical planes passing through the passengers in both longitudinal (A, B, C) and transverse direction (1, 2) and one horizontal plane passing at the level of the breathing zone (D). Figure 16: Comparison between distributions of the velocity magnitude \(V\) [m/s] at different axial distances from the exit plane of the PV nozzle: (1) experimental [52], (2) CFD [52], (3) CFD (present study); (**a**) 0.5\(D_{e}\), (**b**) 1\(D_{e}\), (**c**) 1.5\(D_{e}\); (**d**) axial velocity comparisons between the three cases. Figure 17 displays the flow fields in the cross-section across the two rows and in the longitudinal section along the seats. A large circulation pattern is formed on the sides of the cabin, with the vortex center above the heads of the passengers. The velocity in the jet regions is higher, while the velocity in the center of the cabin is lower. In the region of the passengers, the maximum velocity magnitude is 0.2 m/s, which is consistent with the requirements for an aircraft cabin. The passengers on the right side are found in a downward flow of the circulation pattern, while the passengers on the left side are found to be in the upward flow. With the downward air supply from the ceiling above the seats, the airflow was not vertical but shifted towards the front seats. In the longitudinal section, most of the airflow is downward because of the circulation pattern. The velocity magnitude near the passengers' heads is low because the upward thermal plume counteracts the  
Figure 17: Distribution of velocity and temperature inside the modeled domain in the case without personalized ventilation. Vertical planes passing through the passengers: A,B,C—longitudinal direction; 1,2—transversal direction. Vertical plane passing through the breathing zone: D.  
downward general flow. The velocity distribution is not exactly the same in front of all the virtual passengers. Figure 17 also displays the temperature distributions in the same sections as were presented for velocity. The temperature distribution is relatively uniform, except in the ventilation jet and above the heads of the manikins. The air temperature is slightly higher above the manikins because of the thermal plume created by the released heat. The thermal plumes above the virtual passengers in different seats varies slightly in the longitudinal section, as shown in Figure 17, which indicates the unstable nature of the flows in these regions. Figure 18 presents the velocity and temperature distributions for the numerical cases with the PV diffuser installed near the breathing zone of one of the passengers. Contours are presented in vertical planes passing through the passengers in transverse direction (1, 2) and longitudinal direction on the second seats row (A). Another vertical plane is slicing through the PV diffuser (B).The general pattern of the flow within a recirculation region is maintained in this case, and the temperature and velocity distributions are similar to those of the previous case, except for the region around the virtual passenger with a personalized ventilation system. In this case, the influence of the PV flow in front of the face of the targeted occupant can be clearly distinguished. The jet flow delivered from the PV diffuser has low momentum and is entrained by the convective layer around the body of the virtual manikin in such way that it delivers air to the face of the virtual passenger. Given the fact that the purpose of the PV diffuser is to supply fresh air to the occupant, it is of interest to place the flow in the context of the definition of the physical boundaries of the breathing zone.