A new description of "diameter effect" in pipe flow of surfactant solutions

On the basis of our experimental investigations it was found that proximate causes of an appearance of scale effect should be connected with rheological properties of surfactant solutions and especially with the critical value of shear rate above which the formation the fluid structure of SIS follows. If the value of critical shear rate becomes exceeded in the laminar range of flow, the system achieves the maximal drag reduction in a flow for a given surfactant solution. In case when it takes place in the turbulent range, at a given value of Reynolds number in the pipe of bigger diameter the smaller decrease of friction factor has been observed. We propose for description of "diameter effect" the relation between DR or DDR factors and dimensionless velocity wr.