The diameter effect in drag reduction

A simple mechanism is suggested for providing a quant. explanation of the so-called diam. effect in drag redn. Equations are derived from the rheological equation of state of a Maxwell fluid (W. L. Wilkinson, 1960) and indicate that the viscoelastic behavior of a Maxwell fluid is closely related to the value of the dimensionless quantity wt, where w = the angular frequency and t = the relaxation time. If 1/w is interpreted as a characteristic flow time of the disturbances created by the eddies, then wt represents the ratio of a relaxation time to a characteristic flow time and consequently, takes the form of a Deborah no. as defined by M. Reiner (1964). [on SciFinder (R)]