AI 中文总结
研究裂隙多孔介质中机械诱导相变问题，提出持久变量框架及等容热力学预处理方法，推导相关模型，通过实验对比表明该方法能解决瞬态汽化等问题，揭示平衡规范对数值特性的影响及预处理与热力学的联系。
AI 中文摘要
快速的孔隙体积变化会在短于特征传输时间的时间尺度上触发相变，传统非线性求解和自适应时间步长可能会跳过。本文提出了一个用于裂隙多孔介质传输的持久变量框架，引入比容作为自变量。从全耦合系统出发，推导基于体积的模型并通过消除局部热力学变量恢复经典基于压力的公式。为解决突然的裂隙张开，引入非线性预处理器，通过等容平衡计算解决流体状态。研究表明，未预处理的模拟会错过瞬态汽化，而预处理模型则不会。热效应改变相演化，但对整体瞬态持续时间影响较小。在概念验证设置中，裂隙张开会产生显著的瞬态压力降低，压力 - 焓和体积 - 温度公式恢复相同物理解，但非线性鲁棒性不同。这些结果表明平衡规范控制非线性问题的数值特性，而非恢复的物理响应，等容预处理将非线性初始化直接与基础热力学联系起来。
英文摘要
Rapid pore-volume changes can trigger phase change on timescales shorter than characteristic transport times and may therefore be skipped by conventional nonlinear solves and adaptive time stepping. We present a persistent-variable framework for transport in fractured porous media, introducing specific volume as an independent variable. Starting from a fully coupled system, we derive volume-based models and recover classical pressure-based formulations by eliminating local thermodynamic variables. To resolve abrupt fracture opening, we introduce a nonlinear preconditioner that assumes instantaneous free expansion and resolves the fluid state through an isochoric equilibrium calculation before advancing the transport problem. The preconditioner applies to both volume- and pressure-based models. In the studied fracture-opening cases, unpreconditioned simulations miss transient vaporization, whereas the preconditioned models do not. Across the investigated aperture range, larger openings produce monotonic increases in gas content, expansion-induced cooling, and durations of transients. Thermal effects alter the phase evolution but have otherwise minor influence on the overall transient duration. Within the proof-of-concept setting, fracture opening generates substantial transient pressure reductions, indicating that geomechanical feedback may become important in fully coupled applications. Pressure-enthalpy and volume-temperature formulations recover identical physical solutions but exhibit different nonlinear robustness, with the pressure-enthalpy formulation proving more robust in some recompression-dominated cases. These results show that equilibrium specifications control the numerical properties of the nonlinear problem rather than recovered physical responses, while isochoric preconditioning connects the nonlinear initialization directly to the underlying thermodynamics.
Comments26 pages, 12 figures, source code: https://doi.org/10.5281/zenodo.21433114
