Liquid cooling is an important heat transfer technique that enhances the thermal management of cooling systems across various practical applications. In this research, our goal is to improve the design of NASA's cooling systems used for spacecraft, aiming for greater energy efficiency and cost-effective solutions. To achieve this, we conducted CFD Direct Numerical Simulations using FC72 as a liquid refrigerant. Our in-house DNS solver was employed to simulate saturated, subcooled, and superheated pool boiling, revealing a coupling effect between heat transfer and bubble dynamics [1, 2]. The visualizations show that rising bubbles generate a vortex pair in their wake, inducing turbulent mixing. For subcooled pool boiling, depending on the bulk liquid temperature, coherent structures are dominated by mushroom-like vortices or ring vortices farther from the wall. Near-wall interactions, however, are independent of the bulk temperature and exhibit vortex patterns. For superheated pool boiling, irregular pattern vortices have been observed at both near-wall interactions and further away from the wall. These coherent vortices have been visualized by computing the Q-criterion as follows: Q = 1/2 (▽.u2 - ▽u:▽uT)[1] Youssoufi, S., Lentner, A., Riaz, A., Balaras, E., 2023. A study of subcooled pool boiling using Direct Numerical Simulations. Proceedings of the 4th International Conference on Fluid Flow and Thermal Science (ICFFTS'23), Lisbon, Portugal, December 07-09, 2023, DOI: 10.1159/icffts23.169.[2] Youssoufi, S., Riaz, A., Balaras, E., 2024. Heat transfer and bubble dynamics behaviors in subcooled pool boiling at earth and ISS gravity using high-fidelity CFD simulations. Proceedings of the 34th Thermal and Fluid Analysis Workshop (TFAWS'2024), NASA-GRC Glenn Research Center, Cleveland, Ohio, August 26-30, 2024.
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