Eur. Phys. J. Plus (2017) 132: 125
https://doi.org/10.1140/epjp/i2017-11401-5

Regular Article

A novel explicit equation for the friction factor prediction in the annular flow with drag-reducing polymer

¹ Department of Mechanical Engineering, Hakim Sabzevari University, Sabzevar, Iran
² Department of Civil Engineering, Hakim Sabzevari University, Sabzevar, Iran

^* e-mail: e.lakzian@hsu.ac.ir

Received: 22 November 2016
Accepted: 5 February 2017
Published online: 14 March 2017

Abstract

In this paper, a novel explicit equation is presented for the friction factor prediction in the annular flow with drag reducing polymer (DRP). By using dimensional analyses and curve fitting on the published experimental data, the suggested equation is derived based on the logarithmic velocity profiles and power law in boundary layers. In the next step, a least squares method is used to calibrate the presented equation. Then, the equation is used to friction factor prediction of the gas-liquid mixture with DRP and the results are compared with the experimental data and the Al-Sarkhi ones. Finally, drag reduction (DR) is applied as the ratio of the friction factor reduction using DRP to the friction factor without DRP. The DR results show that the suggested equation has a better agreement with the experimental data in comparison with the pervious equations. The results also show that DR prediction decreases with the increase of the gas superficial velocity.