How to calculate drag coefficient of the model

[20415044mm]

Hello,
I am currently calculating the drag coefficient of a rectangular prism model placed in a uniform flow. However, the result I obtained is 1.3, which is smaller than the value reported in previous studies (approximately 2.0).

The parameters I used for the calculation are as follows:

• Wind velocity: 32 m/s (assumed constant with height)

• Model dimensions: width × depth × height = 10.24 m × 10.24 m × 37.42 m

• Air density: 1.22 kg/m³

I have uploaded my model data at the link below. I would greatly appreciate it if you could kindly review it and let me know where I might be making a mistake.

https://drive.google.com/drive/folders/1tYOPzNB17_d6Wdnz1oEJzdrUBdXFSBN_?usp=drive_link