Print Email Facebook Twitter Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls Title Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls Author Ebrahimi, Amin (TU Delft Team Marcel Hermans) Shahabi, Vahid (Ferdowsi University of Mashhad) Roohi, Ehsan (Xi’an Jiaotong University) Date 2021 Abstract Gas flow and heat transfer in confined geometries at micro-and nanoscales differ considerably from those at macro-scales, mainly due to nonequilibrium effects such as velocity slip and temperature jump. Nonequilibrium effects increase with a decrease in the characteristic length-scale of the fluid flow or the gas density, leading to the failure of the standard Navier–Stokes–Fourier (NSF) equations in predicting thermal and fluid flow fields. The direct simulation Monte Carlo (DSMC) method is employed in the present work to investigate pressure-driven nitrogen flow in divergent microchannels with various divergence angles and isothermal walls. The thermal fields obtained from numerical simulations are analysed for different inlet-to-outlet pressure ratios (1.5≤Π≤2.5), tangential momentum accommodation coefficients, and Knudsen numbers (0.05≤Kn≤12.5), covering slip to free-molecular rarefaction regimes. The thermal field in the microchannel is predicted, heat-lines are visualised, and the physics of heat transfer in the microchannel is discussed. Due to the rarefaction effects, the direction of heat flow is largely opposite to that of the mass flow. However, the interplay between thermal and pressure gradients, which are affected by geometrical configurations of the microchannel and the applied boundary conditions, determines the net heat flow direction. Additionally, the occurrence of thermal separation and cold-to-hot heat transfer (also known as anti-Fourier heat transfer) in divergent microchannels is explained. Subject Poiseuille micro-flowthermal field analysisheat flowdivergent microchanneldirect simulation Monte Carlo (DSMC) To reference this document use: http://resolver.tudelft.nl/uuid:f157e491-5e32-4b24-b691-9613a98d69ea DOI https://doi.org/10.3390/app11083602 ISSN 2076-3417 Source Applied Sciences, 11 (8) Part of collection Institutional Repository Document type journal article Rights © 2021 Amin Ebrahimi, Vahid Shahabi, Ehsan Roohi Files PDF applsci_11_03602.pdf 4.66 MB Close viewer /islandora/object/uuid:f157e491-5e32-4b24-b691-9613a98d69ea/datastream/OBJ/view