Non-Newtonian Fluids Flow in a Circular Pipe

Abstract

High molecular weight polymer solutions or surfactant solutions are typical examples of complex fluids. They exhibit nonlinearity in viscosity and drag reduction occurs in the turbulent pipe flow even if the concentration is very dilute. They are generally known as non-Newtonian fluids. By applying a hydrophobic wall pipe to reduce drag on the flow of polymer solutions, a flow system was constructed, wherein drag reduction was obtained in both the laminar and turbulent flow ranges. In discussions of Newtonian fluid in Chapter 2, we dealt with apparent slip flow analytically using Navier’s hypothesis, and the result was compared with the experimental findings of the friction factor. The experimental results of PEO (polyethylene oxide) aqueous solutions with a concentration range of 30-1000 ppm and the analytical result for the friction factor of a power-law fluid with fluid slip were analyzed by applying the modified boundary condition on fluid slip, as described in this chapter.

Keywords: Drag reduction, laminar flow, complex fluid, turbulent drag reduction, pipe flow, friction factor, highly water-repellent wall, slip velocity, power-law model, polyethylene-oxide solutions, surfactant solutions, contact angle.