This research project will examine the possibility that a non- Newtonian (viscoelastic) fluid may enhance heat transfer while reducing drag and pressure drop. This thesis will be explored in experiments on a complex pipe flow--the flow downstream of a sudden enlargement in a circular pipe. The experiments will encompass both laminar and turbulent flow and will include both fluid flow and heat transfer measurements. A second objective of the project is to develop an advanced, degradation-free non- Newtonian fluid based on a surfactant additive.