Methods and systems for establishing Taylor-Couette flow in a fluid are provided. Aspects of the disclosed methods and systems incorporate Taylor-Couette flow in combination with a source of radiation to provide more uniform radiation exposure to the fluid and its components. Common problems of non-uniform radiation levels and concentration boundary layer effects in UV reactors are largely eliminated using the methods and devices provided herein. In an exemplary embodiment, the reactor of the present disclosure has a hollow outer cylinder or stator and a rotor positioned therein and smooth walls for both the outer wall of its rotor and the inner wall of the outer cylinder or stator in which the rotor is positioned, the space between which forming the annular fluid gap. In an alternative embodiment, either the surface of the outer wall of the rotor or the surface of the inner wall of the outer cylinder or stator or both wall surfaces could be corrugated or furrowed such that they have a series of alternating peaks and valleys. This "wavy wall" embodiment provides a more uniform dosage to the fluid parcels formed within the annular gap of the reactor than the smooth wall embodiment.