Airflow management is a critical aspect of data center thermal management. This is essential for achieving uniform airflow and effective cooling. In recent years, fan wall cooling (FWC) system have gained popularity in air-cooled data centers. While existing research primarily focus on optimizing, a comprehensive assessment of their airflow issues is needed for further refinement. This study uses simulations to explore the airflow characteristics in data centers with FWC system, identifying phenomena such as hotspots within racks, airflow pulsations in the cold aisle, and uneven velocity and temperature distribution. Comparative analysis with raised-floor cooling revealed that FWC system improved uniformity by nearly 82%, reduced the SHI to 0.2, and decreased the RTI by 4.5%. However, limitations such as vortex airflow and hotspots at the front and rear of the racks were easy to occur.