UNS: Heat Transfer in Granular Flows: Understanding Similarities and Differences with Molecular Fluids

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The proposed study aims at understanding why particles in fluid might or might not enhance heat transfer for surfaces. The investigator will examine results from models and experiments to shed lights on existing conflicting work. Part of the proposed plan is to engage undergraduates and high school students in separate, small research projects aimed at the magazine Annals of Improbable Research (AIR) with an editorial board that includes several Nobel Prize winners. AIR has a tagline "research that makes people laugh and then think," designed to motivate a broader range of students to gain experience in scientific research, as well as a means for making science more accessible and exciting for the greater public. The PI proposes to develop numerical models and experimentally validate the numerical models (and the associated hypotheses) for application of granular flows in enhancing heat transfer during two-phase flows. The existing experimental results in the literature perplexedly indicates heat flux does not scaling monotonously with Peclet number. The proposed research aims at resolving such a contradiction and is thus intriguing. This work builds on recent research involving multi-phase flows but adds complex approaches involving granules with different shapes, surface roughness, slip velocities, and flow instabilities. The hypotheses to be tested are: (1) the discrepancy in existing data sets in the literature for macro-level quantities (heat transfer coefficient) can be traced to micro-level characteristics, such as surface roughness and tomography; (2) an increase in particle mobility can lead to reduced heat transfer due to reduced contact time with boundary; (3) the presence of flow instabilities may attenuate heat transfer due to increased particle mobility and thus decreased contact.