A mercury-in-glass thermometer at 40C (OD = 1 cm) is inserted through a duct wall into a

Question:

A mercury-in-glass thermometer at 40°C (OD = 1 cm) is inserted through a duct wall into a 3 m/s airstream at 66°C. This can be modelled as a cylinder in cross-flow, as shown in the figure. Estimate the heat transfer coefficient between the air and the thermometer.