## 4 URANS Data on Airflow
### Comparison of CFD and Experimental Data  
The CFD velocity magnitude data were collected at the four points for which the experimental data are available. For both the cases, the samples of 7500 s correspond to the self-oscillations with the invariant mean value, i.e., the statistically developed regime.  
Figure 6 compares the evolution of computed and measured velocity magnitude for case #2, \(\theta=25^{\circ}\). The entire measured sample of one hour is given in the plot; the computed sample is presented partially. As the URANS technique resolves only low-frequency pulsations, the time-averaged measured velocity data with the averaging period of 1 min, \(<\)\(V\)\(>\)\({}_{60\text{ s}}\), are used for comparison. This type of measurement data processing filters the high frequencies that are useless for the URANS data validation. The low-frequency pulsations kept in the experimental data after processing are reproduced qualitatively in the URANS computations, though there is some quantitative difference. Thus, at the highest point, at \(z=1.7\) m (Figure 6d) the period of the oscillations is approximately 300 s in the numerical solution and approximately 200 s in the experimental data. The large amplitude of the measured pulsations at this point is attributed to the non-isothermal effects; if the temperature quasi-steady-state period in the time interval [1200, 2700] is considered, the measured amplitude is lower than the computed one. The amplitude of the pulsations obtained in CFD simulation is also higher than the measured amplitude at the lowest point, at \(z=0.1\) m (Figure 6a); the satisfactory agreement between the computed and measured frequencies is demonstrated. On the contrary, at the remaining two points higher amplitude of pulsations is obtained in the measurements. The main  
Figure 5: Instantaneous velocity magnitude at various cross-sections in two moments of time: (**a,b**) \(t=t_{0}\) and (**c**) \(t=t_{0}+5000\) s (data for \(\theta=25^{\circ}\), case #2).  
conclusion is that both the experimental and computational data confirm the low-frequency pulsations in the occupied zone that is very important for the thermal comfort evaluation.  
The computed and measured mean velocity data are compared in Figure 7. The computed data, extracted from the time-averaged computational solution, are presented as solid lines covering the whole room height (both the jet zone and the occupied zone). The symbols illustrate all the experimental data available for the occupied zone.  
The comparison performed for the two cases demonstrates perfect agreement between the measured and computed mean velocity data at the three lower points, \(z\leq 1.1\) m. The non-isothermal effects influence the values of \(<\)\(V\)\(>_{3600\,\mathrm{s}}\), resulting in some increase in the values as compared with \(<\)\(V\)\(>_{3600\,\mathrm{s}}\) (Figure 7a). The largest difference between the measured and computed data is seen at the highest point, \(z=1.7\) m. This difference could occur due to the point being not far from the jet, especially for case #3 (Figure 7b), and the non-isothermal effects could be more pronounced there.  
Figure 6: Time evolution of velocity magnitude at four monitoring points: (**a**) \(z=0.1\) m, (**b**) \(z=0.6\) m, (**c**) \(z=1.1\) m and (**d**) \(z=1.7\) m (data for \(\theta=25^{\circ}\), experimental case #1 and computational case #2).  
Figure 7: Comparison of the computed mean velocity profile with the experimental data, (**a**) \(\theta=25^{\circ}\), case #2, and (**b**) \(\theta=45^{\circ}\), case #3.