(3)說明 Reynolds number 之物理意義。爲何 Reynolds number 大,流場傾向於 Turbulent Flow ? Reynolds number 小,流場傾向於 Laminar Flow ? (8 分）

(9) The drag force, F, on a smooth sphere depends on the relative velocity, V，the sphere diameter* D, the fluid density, p, and the fluid viscosity, Obtain a set of dimensionless groups that can be used to correlate the experimental data. (Note: dimensional analysis) (20 )