One of the methods currently used to increase pipeline transfer capacity, when the option of extra loops or pumping stations is unavailable, is the use of the drag-reducing agents (DRA).
DRA are long-chain polymeric compounds that reduce turbulent frictional losses. Nowadays there is no complete theory that explains this phenomenon, known as the Toms effect. In the course of the DRA flow in a pipeline the efficiency of the turbulence suppression decreases, most likely due to breakup of the long molecular chains into shorter ones.
In this paper a mathematical model of viscous liquid motion containing DRA is proposed. The model takes into account the gradual breakup of DRA in a pipeline flow. The influence of DRA is considered as a dependence of hydraulic resistance coefficient on the DRA concentration; the DRA concentration in turn depends on a travel distance in a pipeline.