Rheological Aspects of the Design of Technological Process Equipment - Internal Flows

Abstract

Frictional pressure drop for flow of incompressible fluids is traditionally expressed in terms of the Fanning friction factor,

$$f = \frac{{D{}_e\Delta p}} {{2\rho u^{\text{2}} L}}$$

(1)

where p,u and L stand for the fluid density, mean volumetric velocity and length of the duct. The equivalent diameter D_e=4S/O is defined by the duct cross-sectional area S and the wetted perimeter O. For non-Newtonian fluids, the friction factor for most internal flows may be expressed as f = F(Re_G,є) where ReG is a suitably defined generalized Reynolds number and є is the relative roughness of the duct. The F-function is usually called the hydraulic characteristic.