question_answer

The equivalent diameter D of a circular duct corresponding to a rectangular duct having longer side ?a? and shorter side ?b? the same velocity and pressure drop is given by:

A) \[D=\frac{a+b}{ab}\]               

B) \[D=\frac{ab}{a+b}\]

C) \[D=\frac{(a+b)}{2ab}\]           

D) \[D=\frac{2ab}{a+b}\]