# Optimization of Airflow Organization in Bidirectional Air Supply Data Centers in China
## 4 Airflow Organization Optimization
### Analysis of the Optimized Data Center Flow Field  
Figure 10 presents the velocity distributions at the mid-section (x = 5.7 m) of the rack rows under different optimization strategies compared with the baseline model. \begin{table}
\begin{tabular}{c c c} \hline
**Category** & **Index** & **Optimization Contents** \\ \hline \multirow{4}{*}{Individual optimization strategies} & Case1 & Cold aisle door-only containment \\  & Case2 & Cold aisle top-only containment \\  & Case3 & Fully contained cold aisle containment \\  & Case4 & Rack blanking panels \\  & Case5 & Rack blanking panels + Cold aisle door-only containment \\  & Case6 & Rack blanking panels + Cold aisle top-only containment \\  & Case7 & Rack blanking panels + Fully contained cold aisle containment \\ \hline \end{tabular}
\end{table} 
Table 4: Airflow optimization strategies. Figure 9: Temperature contour plots of the baseline model. Case1 demonstrates negligible influence on the airflow patterns in the central zone of the computer room. Case2 effectively isolates the hot air recirculation from the aisle top while confining the rack-induced hot air reflux within the cold aisles. Concurrently, the cold airflow increases in both cold side aisles AB and GH at this cross-section, while excessive cold airflow in cold aisle CD bypasses into adjacent hot aisles through rack gaps. Case3, when compared to Case2, shows no improvement in addressing the reflux issue through unoccupied rack spaces, with severe cold-hot air mixing persisting. Case4 demonstrates that the underfloor air supply in cold aisles CD and EF is no longer obstructed by rack exhaust flows, enabling effective delivery to the aisle tops without significant temperature rise. However, excessive cold air escaping from the cold aisles mixes with hot air in the upper space, resulting in cooling capacity loss. Furthermore, cold aisle AB shows insufficient cold air supply, failing to effectively mitigate the hot air recirculation phenomenon in its upper section. In cold aisle GH, the vertical travel distance of perforated tile airflow increases, partially alleviating upper-level hot air recirculation and consequently improving cooling efficiency for upper rack servers. The blanking panel installation prevents localized recirculation of rack exhaust through rack gaps. Instead, the heated air rises to the ceiling under buoyancy effects, forming intense vortex fields when obstructed by the overhead structure. In the combined optimization strategies, all configurations incorporate the blanking panel installation at rack intake sides, which effectively segregates the internal airflow paths between cold and hot streams within the server racks. This implementation results in more distinct airflow streamline distributions throughout the aisles. Figure 10: Data center flow fields under different optimization strategies. (**a**) Case1; (**b**) Case2; (c) Case3; (**d**) Case4; (**e**) Case5; (**f**) Case6; (**g**) Case7. Compared with Case4, Case5 demonstrates no significant improvement in airflow organization patterns, showing persistent hot air recirculation at the top of the racks in both cold aisle AB and cold aisle GH without observable mitigation. Case6 effectively isolates the recirculated hot airflow from the upper sections of cold aisles AB and GH, enabling the unobstructed delivery of cold airflow to the mid-upper portions of the aisles, thereby achieving efficient server cooling. Furthermore, this solution addresses the cold airflow bypass issues at the tops of cold aisles CD and EF. The analysis reveals a reduction in floor-supplied airflow volume in cold aisle CD at this cross-section, while the excess cold air in cold aisle EF deflects upon reaching the aisle top and redistributes to other regions of the cold aisle. Case7 achieves complete isolation between cold and hot air streams in the computer room. The pressure drop in the cold aisle increases, optimizing pressure distribution in the plenum.