Clear existence of three drag reduction zones was observed: stable transitional zone, unstable transitional zone and in particular the third turbulent drag reduction zone.The dominant factor which influenced DR in the transitional zone was the addition of CTAB + NaSal. In the third zone, the addition of PEO had decisive influence on the DR intensity. The increase of PEO concentration enhanced DR in this zone.The influence of pipes diameter on the DR was investigated. The increase of pipe diameter caused clear extension of the stable transitional zone. In the third zone DR increased while decreasing pipe diameter.Analyses showed that the value of the n flow index was not an important factor in the DR.The results indicate that polymer-micellar solutions combine and intensify positive features of their pure polymer and micellar equivalents, providing efficient DR in a wider range of the Reynolds numbers.

-The main aim of this paper is to present a possibility to enhance the drag reduction effect in straight pipe flow by the simultaneous addition to the transported liquid of a small amount of high molecular weight polymers and surfactants. Qualitative analysis of the polymer-micellar additive influence on the shape and character of flow resistance curves has been performed. Also multicomponent polymer-micellar solution flow resistance curves were compared with appropriate single additive polymer or surfactant solution flow resistance curves. The experimental data shows that, for polymer-micellar solutions, the stable transitional zone between the laminar and the turbulent flow regions is extended toward higher values of the critical Reynolds numbers. Occurrence of the phenomenon can be explained by the flow laminarization caused by polymer-micellar aggregates. Existence of the third extended drag reduction zone in the turbulent range of flow has also been observed for the first time.

Introduction: This paper describes the results of research aimed at developing a method of otolaryngological diagnosis based on computational fluid dynamics, which has been called Virtual Rhinomanometry. Material and methods: Laboratory studies of airflows through a 3D printed model of nasal cavities based on computed tomography image analysis have been performed. The CFD results have been compared with those of an examination of airflow through nasal cavities (rhinomanometry) of a group of 25 patients. Results: The possibilities of simplifying model geometry for CFD calculations have been described, the impact of CT image segmentation on geometric model accuracy and CFD simulation errors have been analysed, and recommendations for future research have been described. Conclusions: The measurement uncertainty of the nasal cavities’ walls has a significant impact on CFD simulations. The CFD simulations better approximate RMM results of patients after anemization, as the influence of the nasal mucosa on airflow is then reduced. A minor change in the geometry of the nasal cavities (within the range of reconstruction errors by CT image segmentation) has a major impact on the results of CFD simulations.

The main aim of this paper is to present possible drag reduction effect application to reduce the energy costs in water transport systems. Results obtained in laboratory scale experiment present possibility to enhance the drag reduction effect in pipe flow by simultaneous addition to the transported water small amount of high molecular polymers and surfactants. The hypothetic mechanism of drag reduction by polymer-micellar aggregates is presented. Qualitative analysis of polymer-micellar additives influence on shape and character of flow resistance curves is performed. Complex polymer-micellar solution flow resistance curves are compared with appropriate single additive polymer or surfactant one.