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Reduction of fluid resistance using the rheological characteristics of a polymer-surfactant solvent is research that contains many aspects, such as the theory of the drag reduction process, historical journey, and ongoing current research development. Many studies have been conducted, but it is challenging to know all existing and new research threads. The present investigation was conducted using literature studies regarding drag reducing agents. This research will also discuss the characteristics of flowing fluids and their effects on the velocity profile with friction factor of flowing fluids in smooth circular straight pipe geometries based on experimental, theoretical approaches. It concludes with aspects of research conducted around reducing drag using drag reducing agents, ideas about innovations, structuring overlook in testing, and modification of the fluid flow state.

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Drag reduction phenomena can be obtained using additive polymer that can generate turbulence damping by fluid movement and characteristic. Measurements were carried out to investigate pressure losses in square and rectangular horizontal ducts coating of additive Agar solution, with aspect ratios (e) = 1.0 and 0.5, respectively. The increment concentrations are ranged up to 2 times and drag reduction effect was obtained up to 1.5 times bigger. This research analysis was done using friction coefficients and Reynolds numbers relation to put forward drag reduction phenomena. The effect of Agar coating delayed the transition regime. The research results using 1 mm of thickness Agar coating with concentration 20% and 40% concentrations were obtained maximum drag reduction phenomena about 19% at the Reynolds number about 2,600.

nergy efficiency is a global goal in the fight against global warming. Research on reducing drag is one of the ways to improve energy efficiency. The research method used is the injection of micro-sized bubbles and ultra-fine bubbles used in the barge ship model. Microbubble Drag Reduction (MBDR) and Ultrafine Bubble Drag Reduction (UFBDR) are two methods that can play an essential role in reducing drag on the surface of the ship's hull. Factors that can affect the effectiveness of these methods are the injection ratio, location, and coefficient of drag produced by both methods. The injection method discussed the use of the method, which was reviewed on a 2-meter towing tank and compared the two injection methods. The results provided by this research are to determine the injection ratio and the optimum injection location on the model ship and compare the effect of reducing drag and drag coefficient. The increases total resistance reduction of 6.87% compared to the reduction in resistance by microbubble injection.