Entropy analysis of concentric annuli with rotating outer cylinder

Abstract

The effects of conduction and heat generation due to viscous dissipation in annuli is a topic of interest to researchers, since the applications include aerospace, food processing, electric machines, etc. In the present study, temperature rise and entropy generation in a cylindrical annuli due to conduction and viscous dissipation are considered. In the mathematical formulation, the flow developed in the annuli is assumed as laminar, since Re is selected as $\text{≤50}\text{000}$. The wall temperature of the rotating cylinder is taken as higher than the wall temperature of the stationary inner cylinder. The temperature and entropy profiles are predicted for different Brinkman numbers and temperature difference across the annuli. It is found that as Br increases, the temperature in the fluid close to the rotating cylinder wall becomes higher than the wall temperature. This results in zero temperature gradient and the entropy generation reduces to zero in this region. The point of minimum entropy generation in the fluid moves away from the outer cylinder wall as Br increases. Moreover, the efficient operation and design of bearing systems can be possible with the analysis of entropy generation.