An array of pin fins made of copper 1 mm in diameter and 3 mm in length will be used in cooling an electronic board prototype. The prototype will be cooled by air at 25C blown by a fan moving at 10 m/s. To verify the designed prototype, a larger scale model is built which is 1.5 cm in diameter and 4.5 cm long. The model will also be cooled by air at 25C. The model and the prototype are expected to have: 1. similar flow and heat transfer characteristics, and 2. consequently, the same fin efficiencies. Find the flow velocity to be used in cooling the model and select an appropriate metal for the model.