The pressure drop (AP) in a pipe depends upon the mean velocity of flow (u), length of pipe (L), diameter of pipe (d), the fluid density (p), and dynamic viscosity (u), average height of roughness on inside pipe surface (e). By using Buckingham's II- theorem obtain a dimensionless expression for (AP). And show that h, = 4f ΔΡ Lu² d 2g where (h) is the head loss due to friction () and (f) is the dimensior less fanning friction factor. pg