%0 Journal Article %T Modification of the Velocity Profiles of Turbulent Flow of Water Using Polymeric Solutions; Experimental Investigation %J Journal of Hydraulics %I Iranian Hydraulic Association %Z 2345-4237 %A Karami, Hamidreza %A Rahimi, Masoud %A Ovaysi, Saeed %D 2019 %\ 01/21/2019 %V 13 %N 4 %P 43-55 %! Modification of the Velocity Profiles of Turbulent Flow of Water Using Polymeric Solutions; Experimental Investigation %K Pressure drop %K Turbulent Flow %K Polymer %K laser Doppler velocimetry %K Velocity profile %R 10.30482/jhyd.2019.82706 %X Low concentration of drag reducing agents have found their efficient applications to reduce requiredenergy of the pipeline turbulent flow transportation. These additives can effect on turbulent structures,and can modify velocity profile, and thus they cause to reduction of the skin friction of the flow. In thepresent study, two commercially available copolymer of polyacrylamide with different molecularweights, were employed to study the possible impact of different concentrations of the polymers onpressure drop reduction of turbulent flow of water in pipeline. The obtained results demonstrated thatboth the copolymer showed high drag reduction along with low degradation rate for 2hr of theexperimentation. Addition of 30ppm of the high molecular weight polymer to turbulent flow showed54% drag reduction. Following the drag reduction measurement, turbulent velocity profiles for theoptimum concentration of the two polymers were obtained by using laser Doppler velocimetrytechnique. The results showed a tendency to laminarization of the flow supported with low amounts ofReynold stresses and velocity fluctuations in the presence of the polymer. In all the cases, the effectsof the higher molecular weight polymer on the velocity profiles of the turbulent flow is more desirablethan lower molecular weight one. %U https://jhyd.iha.ir/article_82706_093f58c371b45e74e6d811f2307937f7.pdf