Drag Reduction by Complex Mixtures in Turbulent Pipe Flows

The drag reduction of high molecular polymer solutions is well known as the Toms effect. The drag reduction can be divided into two types: Type A and B. Type A corresponds to the solutions of synthetic polymers such as polyethylene oxide or polyacrylic amide. In contrast, Type B corresponds to the solutions of biopolymers such as xanthan gum, guar gum, and polysaccharide. Experiments were performed to measure the friction factor and heat transfer coefficient for the aqueous suspensions of graphene oxide thin-plate particles. The results show that the complex fluids exhibit a Type B drag reduction phenomenon in the turbulent flow range. The onset point of the drag reduction was found to be R e f ≅ 260 for Cw = 0.1 wt%. This point increased compared to the experimental results for Cw = 0.5 wt% graphene oxide solutions that have been reported on drag reduction. The velocity profiles of the aqueous suspensions of graphene oxide thin-plate particles and the dried malted rice culture solutions classified as biopolymer were estimated from the experimental data of the friction factor. In general, aqueous suspensions of fine particles are characterized by an increase in the friction factor and the heat transfer coefficient as compared to water. However, the aqueous suspension of the graphene thin-plate particles produces the drag reduction of the friction factor and increases the heat transfer coefficient. Therefore, the experimental results obtained in this study show that graphene oxide shin-plate particle suspensions become a useful carrier for the cooling pipeline system.