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Question 10.2: A silk worm, diameter 4 mm, is suspended vertically on a thr...

A silk worm, diameter 4 mm, is suspended vertically on a thread in a sunfleck in a plant canopy where the windspeed is 0.1 m s^{-1}. If the caterpillar’s temperature is 5 °C greater than the air temperature, estimate its rate of convective heat loss.

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Re= 8\times 10^{-3} \times 0.05/15\times 10^{-6}  =2.7

Gr = 158 × 0.8³ × 5 = 404

Gr/Re² = 55, so heat transfer is dominated by free convection. Assume that Nu = 0.58Gr^{0.25} . Hence Nu = 4.5 and C= 4.5\times 26\times 10^{-3} \times 5/8\times 10^{-3} = 73 \; W \ m^{-2} .

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