(2) °ü³» ¸¶Âû¼Õ½Ç°ú À¯·®°úÀÇ °ü°è½Ä Darcy(Moody)'s EquationÀ¸·ÎºÎÅÍ
Pressure Head Loss (due to Skin Friction)= (¥ÄPs)/¥ñ = f *(L/D)* (V^2/2gc)..............................(1)
(friction factor, f )= (¥ÄPs)/¥ñ/(L/D)/(V^2/2gc) = (Sheer Stress at Pipe Wall)/(¥ñ V^2/2gc).........(2)
Ãþ·ù¿µ¿ª f = 16/Re (Hagen-Poiseuille)
ïÂ춿µ¿ª f = 0.0004 Re^0.575 (T.G. Serghides)
³·ù¿µ¿ª f = g(¥å/D, Re) (Moody)....Friction Factor Chart