A NUMERICAL STUDY ON HEAT-TRANSPORT IN TURBULENT COUETTE FLOWS IN CONCENTRIC ANNULI

A numerical study is performed to investigate turbulent Couette flow a nd heat transfer characteristics in concentric annuli with a slightly heated inner cylinder moving in the flow direction. A tyro-equation k- epsilon turbulence model is employed to determine the turbulent viscos ity and the turbulent kinetic energy. The turbulent heat flux is expre ssed by Boussinesq approximation in which the eddy diffusivity for hea t is given as functions of the temperature variance t(2) and the dissi pation rate of temperature fluctuations epsilon(t) together with k and epsilon. The governing boundary-layer equations are discretized by me ans of control volume finite-difference technique and numerically solv ed using a marching procedure. It is disclosed from the study that the streamwise movement of the inner core causes substantial reductions i n the turbulent kinetic energy and the temperature variance, particula rly near the inner wall region, resulting in the deterioration of the Nusselt number, and that an attenuation in heat transfer performance i s induced by the velocity ratio of the moving inner cylinder to the fl uid flow.