Abstract
Pressure drops of water and surfactant solutions and their drag reduction effects were investigated in slit flows. For water, the resultant pressure drops agreed with the numerical predictions. For aqueous solutions of surfactants, the experimental results differed according to their polarity. Cationic surfactant caused the biggest decrease from the predicted values, followed by non-ionic surfactant. Anionic surfactant gave the same results as water. These effects were attributed to a liquid-solid interface phenomena.
