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基于直接数值模拟的圆盘状颗粒曳力模型研究

DIRECT NUMERICAL SIMULATION OF DRAG MODEL OF DISK-SHAPED PARTICLES

  • 摘要: 圆盘状颗粒广泛存在于自然界和工业环境中, 现有文献对于适用于工业应用场景的圆盘状颗粒曳力模型的研究还不够完善. 为扩展现有模型的适用范围, 基于颗粒辨析直接数值模拟(PR-DNS)对流场内圆盘状颗粒的曳力系数及绕流特性开展研究. 采用OpenFOAM-贴体网格法计算低宽长比下(0 < Ar < 1), 较宽雷诺数(Re≤1000)和入射角(0°≤θ≤90°)范围内圆盘状颗粒的曳力系数, 通过遗传算法(GA)全局最优计算提出了一种新型的曳力系数关联式. 研究表明, 圆盘状颗粒的绕流特性受到宽长比、雷诺数和入射角三种关键因素的共同影响, 雷诺数的增加显著增强了流动的不稳定性, 而入射角和宽长比则通过影响颗粒的投影面积来改变颗粒的曳力系数和绕流特性. 数值验证结果表明, 综合考虑三种关键参数后的新关联式表现出较高精度, 其均方根误差为0.2993, 平均相对误差为4.16%, 且在与现有文献报道中的圆盘状颗粒曳力系数关联式的比较中, 具有良好的一致性. 该关联式完善了现有模型的不足, 为圆盘状颗粒的计算流体力学(CFD欧拉-拉格朗日)数值模拟和工程应用提供了可靠的理论支持.

     

    Abstract: Disk-shaped particles are widely found in nature and industrial environments. Existing literature lacks a comprehensive study on drag models for disk-shaped particles applicable to industrial application scenarios. To expand the applicability of the existing model, this paper investigates the drag coefficients and flow characteristics of disk-shaped particles in a flow field based on particle-resolved direct numerical simulation (PR-DNS).The OpenFOAM-body-fitted mesh method is adopted to calculate the drag coefficient of disk-shaped particles with low aspect ratios (0 < Ar < 1), Reynolds numbers (Re≤1000), and incidence angles (0°≤θ≤90°). A new drag coefficient correlation is proposed using genetic algorithm (GA) optimization. Results show that the flow characteristics around disk-shaped particles are jointly affected by aspect ratio, Reynolds number, and incidence angle. The increase of Reynolds number significantly enhances the flow instability, while incidence angle and aspect ratio alter the particle's projected area, thereby changing its drag coefficient and flow characteristics. Numerical verification indicates that the new correlation has high accuracy, with an RMSE of 0.2993 and a mean relative error of 4.16%. It shows good consistency with existing drag coefficient correlations for disk-shaped particles. It improves the existing models and provides reliable theoretical support for computational fluid dynamics (CFD Eulerian-Lagrangian) numerical simulation and engineering applications of disk-shaped particles.

     

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