申論題

5.

(b) In order to predict the torque on a disc 0.5 m diameter which rotates in oil at 200 rpm, a model is made to a scale of 1/5. The model is rotated in water. Calculate the speed of rotation for the model which produces dynamic similarity. (Oil's density and dynamic viscosity are 750 kg/m³and 0.2 N-s/m², respectively; water's density and dynamic viscosity are 1000 kg/m³ and 0.001 N-s/m², respectively) (10%)