Vertical concentration distribution of fine settling particles in a pulsatile laminar open channel flow

• Published in: European journal of mechanics, B, Fluids Vol. 109; pp. 309 - 323
• Main Authors: Dhar, Subham, Poddar, Nanda, Mondal, Kajal Kumar
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.01.2025
• Subjects: Homogenization method; Open channel; Pulsatile flow; Settling particles; Transverse uniformity; Settling particles; Homogenization method; Pulsatile flow; Transverse uniformity; Open channel
• DOI: 10.1016/j.euromechflu.2024.10.015
• ISSN: 0997-7546

Sedimentation in river and drainage systems frequently increases flood risks, making the study of particle dispersion crucial for effective flood damage control. In the present research, the transport of fine settling particles in a laminar, periodic flow through an open channel is analytically investigated using the multi-scale homogenization method. To investigate how settling velocity affects the dispersion process of fine particles in a tidal wetland, Dhar et al. (2022) studied the dispersion coefficient and mean concentration of the settling particles applying the method of moments. The mean and transverse real concentration distributions of settling particles are analytically derived from the governing equation, and the influence of settling velocity, oscillation Reynolds number, and Schmidt number on the dispersivity and concentration profile of the settling particles is investigated. The results show a vertical non-uniformity of longitudinal concentration distribution due to the introduction of settling velocity. It is also observed that the sedimentation effect for purely oscillatory flow is negligibly small compared to that of the steady and oscillatory flow with a nonzero mean. Pulsatile behavior is observed in the difference rate profile between Taylor’s mean and present mean concentration. The study sheds light on the behavior of settling particles and can be useful for understanding sedimentation and wastewater treatment processes. •Vertical variation for transport of sediment particles in a pulsatile laminar open channel flow is demonstrated.•The settling effect on concentration distribution is small for purely oscillatory flow.•The fine particles concentrated more near the source for tidal flow compared to other flow conditions.•The longitudinal spreading of particles decreases with increasing oscillatory Reynolds number and Schmidt number.•The flow geometry significantly influences the vertical variation rate of settling particles.