Review on methods of drag reduction for two-phase horizontal flows

Abstract

This paper suggests and discusses different drag reduction methods for two-phase horizontal flows through pipes. Two-phase flows are the simplest and most common among the multiphase flows, and have a great importance in real life. Drag reduction can be achieved through the addition of drag reducing additives or agents in the flow system and such method is known as additive method. Drag reducing agents include solid suspensions, polymers and surfactants. Two types of additives exist, soluble and insoluble additives. Insoluble additives include solid suspensions and soluble additives include polymers and surfactants. Nanofluids are also used as drag reducing agents. Combined methods of drag reduction also exist where two different drag reduction methods are used together to achieve drag reduction. The drag reduction is well achieved through solid suspensions, polymers, surfactants and nanofluids. It was also found that combined methods of drag reduction showed more drag reducing ability than methods used separately. From an environmental perspective, the biopolymers are more effective than synthetic ones due to some desirable properties of biopolymers such as cheap, non-toxicity, renewability, bio-degradability, stability, biocompatibility and easy availability.