A new model for predicting drag coefficient and settling velocity of irregularly shaped plant seeds

• Published in: Powder technology 2024-11, Vol.447, p.120201, Article 120201
• Main Authors: Xiaoguang, Liu, Yuhong, Zeng, Bing, Ding, Shuo, Guan, Jiasheng, Wang
• Format: Article
• Language: English
• Subjects: algorithms; Classification method; Drag coefficient; hydrochory; Irregular-shaped seeds; Personalized model; Reynolds number; Settling velocity; system optimization; technology
• ISSN: 0032-5910
• DOI: 10.1016/j.powtec.2024.120201

The terminal settling velocity and drag coefficient are crucial for hydrochory in plant seeds, but predictive models for seeds with highly irregular shapes are rarely studied. The settling velocities and shape characteristics of seven plant seed types are investigated using particle Reynolds number, shape factor, and relative density difference. Irregularly shaped seeds exhibit profile symmetry and sink with their maximum projection area perpendicular to the fall direction, regardless of settling velocity. Irregular-shaped plant seeds are classified into three categories based on elongation-flatness and dimensionless settling velocity, with shape factors proposed for each category. The relationship between drag coefficient and particle Reynolds number of irregular-shaped plant seeds are analyzed in comparison to regular-shaped particles. A global optimization method based on generalized genetic algorithm are used for calibrating the calculation formulas. Compared with other general models, the newly presented formulae predict more accurately the settling velocity of irregular plant seeds. [Display omitted] •New formulas for drag coefficient of irregular plant seeds for various shapes and Reynolds numbers.•Settling characteristics are classified into three types with appropriate shape factors.•One profile of irregular seeds is symmetric, sinking with maximum area perpendicular to fall direction.