Abstract In this work the capabilities of Two Fluid Model simulations coupled with a Population Balance Model solved with the Quadrature Method of Moments in predicting the turbulent kinetic energy dissipation rate and the droplet size distribution in a dilute liquid-liquid stirred tank are investigated. For a strict evaluation of the numerical and modelling approximations, original two-phase flow fields and droplet size distributions are collected by Particle Image Velocimetry and a laser diffraction technique, respectively. The spatial discretization requirements for achieving grid independent and reliable predictions of the turbulent variables already observed in RANS-based simulations of single-phase stirred tanks are confirmed also for the investigated dilute two-phase system, for which the effect of the dispersed phase on the continuous liquid is negligible. Besides, better prediction of the droplet size distribution is apparently obtained with poorly predicted turbulent kinetic energy dissipation rate, showing that the usually adopted parameters of the breakup kernel have been tuned for coarse grids. A way to derive grid independent breakup kernel parameters and a correction based on the spatial distribution of turbulent dissipation rate are proposed to account for the underestimation of the turbulent variables in the RANS simulation of industrial scale equipment.

中文翻译：

---

湍流动能耗散率对搅拌罐中液滴尺寸分布预测的影响

摘要 在这项工作中，研究了两种流体模型模拟结合使用矩量法求解的种群平衡模型在预测稀液-液搅拌罐中的湍流动能耗散率和液滴尺寸分布方面的能力。为了对数值和建模近似值进行严格评估，分别通过粒子图像测速法和激光衍射技术收集原始两相流场和液滴尺寸分布。在基于 RANS 的单相搅拌罐模拟中已经观察到的湍流变量的网格独立和可靠预测的空间离散化要求也得到了研究的稀两相系统的证实，对此，分散相对连续液体的影响可以忽略不计。此外，通过对湍流动能耗散率的预测不佳，显然可以更好地预测液滴尺寸分布，这表明通常采用的破碎核参数已针对粗网格进行了调整。为了解决工业规模设备 RANS 模拟中湍流变量的低估问题，提出了一种导出与网格无关的破碎核参数的方法，并根据湍流耗散率的空间分布进行修正。表明通常采用的分解内核参数已针对粗网格进行了调整。为了解决工业规模设备 RANS 模拟中湍流变量的低估问题，提出了一种导出与网格无关的破碎核参数的方法，并根据湍流耗散率的空间分布进行修正。表明通常采用的分解内核参数已针对粗网格进行了调整。为了解决工业规模设备 RANS 模拟中湍流变量的低估问题，提出了一种导出网格独立分裂核参数的方法，并根据湍流耗散率的空间分布进行修正。