Frictional pressure drop, or drag, is a result of the resistance encountered by flowing fluid coming into contact with the pipe wall. There are generally two types of flow – laminar and turbulent. The friction pressures observed in laminar flow cannot be changed unless the physical properties of the fluid are changed.

The current class of DRA does not change fluid properties and hence is effective only in turbulent flow. In most petroleum pipelines, the liquid flows through the pipeline in a turbulent regime. Therefore, current DRA can perform very well in most pipelines, allowing treatment of light to medium crude, heavy crude, multiphase and refined product applications.

In a turbulent flow regime, the fluid molecules move in a random manner, causing much of the energy applied to them to be wasted as eddy currents and other indiscriminate motion. DRA works by an interaction of the polymer molecules with the turbulence of the flowing fluid.