“…Simple measurements such as viscosity-shear rate data in the laminar region are insufficient. Theories of Drag Reduction Dodge (8, 9) suggested viscoelastic effects as an explanation of the failure of his CMC data to fit Equation 4, and most investigators (2,5,10,13,15,20,22,25,31,40) have preferred his hypothesis. But there is still confusion in the literature regarding earlier theories of drag reduction.…”