Development and Application of Rational Extended Thermodynamics of Dense Gases and Liquids

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K13471
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 13010:Mathematical physics and fundamental theory of condensed matter physics-related
• Research Institution: Tomakomai National College of Technology
• Principal Investigator: Arima Takashi 苫小牧工業高等専門学校, 創造工学科, 准教授 (80735069)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 流体物理 / 非平衡流れ / 拡張された熱力学 / 多原子分子実在気体 / 分子内部自由度緩和 / 特性速度 / 分散関係

Outline of Final Research Achievements

The aim of this study was to understand nonequilibrium phenomena in dense gases and liquids, which is described beyond the assumption of local thermodynamic equilibrium. We achieved this by constructing a theory based on Rational Extended Thermodynamics (RET) and applying it to the analysis of sound wave propagation. We obtained the following main results:
(i) We developed the RET theory for dense polyatomic gases in which the effect of the bulk viscosity is significant. We derived characteristic velocity and specifically investigated its upper and lower bounds, density dependence, and temperature dependence for van der Waals gases.
(ii) Using the derived RET theory, we analyzed the dispersion relation of sound waves. In particular, we successfully demonstrated that the experimental data of sound absorption in liquefied carbon dioxide can be well described by RET compared to conventional hydrodynamics theory, thereby validating the theory.

Free Research Field

非平衡熱力学

Academic Significance and Societal Importance of the Research Achievements

航空宇宙工学における衝撃波解析や医療工学における超音波・衝撃波利用など、流体中の時間・空間的に急激な変化を伴う強い非平衡流れの理解と制御が現代の流体科学・工学において求められている。本研究はこのような学術的・社会的要請に資するものである。本研究の成果は、流体物理・流体工学の幅広い分野への応用可能性がある。