A hybrid CFD-RMD multiscale coupling framework for interfacial heat and mass simulation under hyperthermal ablative conditions

ZF Ye and J Zhao and BJ Zhu and Z Jing and XC Sun and C Stemmer and NA Adams and DS Wen, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, 213, 124341 (2023).

DOI: 10.1016/j.ijheatmasstransfer.2023.124341

Under hypersonic flow conditions, the heat and mass transfer at the gas- solid interface of thermal pro-tection material becomes highly complicated due to the strong chemical and thermal non-equilibrium phenomena, associated with the real gas effect, the high temperature effect and various heterogeneous reactions occurring at the interface or inside the TPM. Interfacial heat and mass transfer is strongly cou-pled with non-linear reactions at different spatiotemporal scales. Based on the traditional macroscopic Computational Fluid Dynamics (CFD) and microscopic Reactive Molecular Dynamics (RMD) methods, a hybrid CFD-RMD multiscale simulation framework is established in this work to improve the accuracy of aerothermal prediction by considering the heat and mass transfer at the gas-solid interface under hyperthermal non-equilibrium conditions. To validate the proposed multiscale framework, phenolic resin composite is investigated in this work with particular interest in the pyrolysis gas injection effects. Bench -marking ablation studies are conducted under three representative altitudes of 40, 60 and 80 km, respec-tively, and the recession rates of 7.47 x 10 -4, 1.53 x 10 -3 and 1.08 x 10 -3 mm/s are obtained which are comparable with the experimental results. Much higher computational efficiency of the hybrid CFD-RMD multiscale framework is achieved comparing to a full RMD simulation method at the same spa-tial and temporal level. Not only to the pyrolysis study, the established framework can also potentially be extended to other gas-solid interfacial reaction situations, which is of great help in improving the mechanism understanding of various physics- derived microscopic models for macroscopic predication of hypersonic aerothermal characteristics. & COPY; 2023 Elsevier Ltd. All rights reserved.

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