用于汽化液-气流动界面分辨模拟的体积分数框架
A volume of fluid framework for interface-resolved simulations of vaporizing liquid-gas flows
AI总结：
本研究提出一套基于体积分数法的汽化液-气流动界面分辨模拟框架，结合无散度外推、锐化场处理等技术，经多维度验证具有一阶收敛性，可准确模拟膜态沸腾、等温蒸发等汽化过程。
摘要：
本研究展示了一套用于模拟汽化液-气流动的计算框架。该框架针对通用汽化问题开发，基于液-气系统的局部热力学平衡求解汽化速率，涵盖了常用的膜态沸腾和等温蒸发两类汽化机制。框架构建于求解低马赫数湍流的笛卡尔网格求解器之上，该求解器经改进后可处理大密度比的多相流动。界面输运采用未分裂的体积分数（volume of fluid）求解器实现，通过一种新型无散度外推技术构建适用于界面输运的速度场；蒸汽质量分数与温度场均采用锐化处理方式，压力泊松方程则采用Ghost Fluid Method（虚拟流体法）求解。界面处的平衡状态通过Clausius-Clapeyron（克劳修斯-克拉佩龙）关系计算，并采用单调、无条件稳定的格式与流动求解器耦合。\n研究表明，界面性质的准确预测是汽化过程高精度模拟的核心基础。研究通过一维、二维和三维的参考解验证了所提数值框架的收敛性与精度：针对通用汽化问题，模拟在时间和空间加密下均能实现一阶收敛。研究最后展示了中等雷诺数下液滴的非定常汽化算例。
英文摘要：
This work demonstrates a computational framework for simulating vaporizing, liquid-gas flows. It is developed for the general vaporization problem which solves the vaporization rate based as from the local thermodynamic equilibrium of the liquid-gas system. This includes the commonly studied vaporization regimes of film boiling and isothermal evaporation. The framework is built upon a Cartesian grid solver for low-Mach, turbulent flows which has been modified to handle multiphase flows with large density ratios. Interface transport is performed using an unsplit volume of fluid solver. A novel, divergence-free extrapolation technique is used to create a velocity field that is suitable for interface transport. Sharp treatments are used for the vapor mass fractions and temperature fields. The pressure Poisson equation is treated using the Ghost Fluid Method. Interface equilibrium at the interface is computed using the Clausius-Clapeyron relation, and is coupled to the flow solver using a monotone, unconditionally stable scheme. It will be shown that correct prediction of the interface properties is fundamental to accurate simulations of the vaporization process. The convergence and accuracy of the proposed numerical framework is verified against solutions in one, two, and three dimensions. The simulations recover first order convergence under temporal and spatial refinement for the general vaporization problem. The work is concluded with a demonstration of unsteady vaporization of a droplet at intermediate Reynolds number.
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