%0 Journal Article %T Drag Reduction by Surfactant Solutions in Gravity Driven Flow Systems %J Iranian Journal of Chemistry and Chemical Engineering %I Iranian Institute of Research and Development in Chemical Industries (IRDCI)-ACECR %Z 1021-9986 %A Subbarao, Chirravuri Venkata %A Phanikumar Yadav,, Yanamala %A King, Pulipati %D 2013 %\ 06/01/2013 %V 32 %N 2 %P 119-123 %! Drag Reduction by Surfactant Solutions in Gravity Driven Flow Systems %K Efflux time %K Cylindrical tank %K surfactant %K Exit pipe %K Froude numbe %R 10.30492/ijcce.2013.5896 %X Efflux time measurements are carried out for gravity draining of a liquid from a large cylindrical tank (where the flow is essentially laminar) through single exit pipe in the absence and presence of Cetyl Pyridinium Chloride (CPC) surfactant solutions. The variables considered are initial height of liquid in the tank, dia. of tank, length of the exit pipe and concentration of surfactant. The dia. of exit pipe in all the cases however remained constant. Drag reduction is expressed as the difference in efflux time in the absence and presence of surfactant solutions. Maximum drag reduction at optimum surfactnat concentration is reported. It is observed that during draining, Froude number remains constant. %U https://ijcce.ac.ir/article_5896_f339efae2239e8dc8ca618feb04a28d4.pdf