RESEARCH PROGRESS ON GAS-SURFACE INTERACTION ACCOMMODATION COEFFICIENTS IN RAREFIED GAS FLOWS

Gas–surface interaction accommodation coefficients quantify the exchange of momentum and energy during molecule–wall collisions. These coefficients are pivotal to modeling boundary effects in rarefied flows, with direct implications for the aerodynamic design and thermal management of near-space vehicles and ultra-low orbit spacecraft. This review synthesizes recent progress on tangential momentum and energy accommodation coefficients across rarefied flow regimes, with emphasis on underlying mechanisms that link microscopic scattering to macroscopic transport and on how these mechanisms are represented in engineering models. By integrating experimental approaches (including the hot-wires method, molecular beam scattering experiments, microchannel flow experiments, and on-orbit measurements) with molecular dynamics simulations that resolve lattice vibration, surface morphology, and molecule adsorption states at the atomic scale, the study identifies the governing laws of accommodation coefficients as influenced by gas properties, surface characteristics and gas–surface interaction potentials. The discussion covers the roles of gas species, mass, incident velocity and angle, and temperature, together with surface roughness, wall temperature, adsorption coverage, and potential well depth. Results indicate that accommodation coefficients are shaped by strong multi-factor coupling: enhanced surface roughness, stronger interaction potentials, and increased gas adsorption generally raise accommodation coefficients, while higher incident energy and system temperature can induce non-monotonic variations by modifying molecular scattering mechanisms. At present, experimental methods provide direct macroscopic measurements with traceability, while molecular dynamics simulations reveal atomistic processes with precise control of surface state and interaction parameters. Nonetheless, challenges remain, including the predominance of single-factor analyses, limited understanding of multi-parameter coupling mechanisms, and inconsistencies between experimental and simulation data. Future efforts should emphasize quantifying surface roughness, characterizing gas adsorption behavior, developing multi-factor coupling models, and validating results under realistic flight conditions, thereby providing more accurate theoretical support for the aerodynamic optimization of next-generation vehicles in rarefied flow environments.