Droplet generation in a co-flowing microchannel influenced by magnetic fields applied in parallel and perpendicular to flow directions

• Published in: Journal of magnetism and magnetic materials Vol. 570; p. 170528
• Main Authors: Fadaei, Mehdi, Majidi, Sahand, Mojaddam, Mohammad
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.03.2023
• Subjects: Co-flowing microchannel; Droplet generation; Field direction; Magnetic field; Co-flowing microchannel; Magnetic field; Field direction; Droplet generation
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2023.170528

•Three-dimensional numerical study of Ferrofluid droplet generation in a coflowing device under magnetic field.•Field direction identified as a decisive factor in determining the drop formation behaviour.•Drop size and speed increased under axial field and mildly decreased under vertical field.•Transitioning from dripping to slug flow regime observed under at high magnetic flux densities in the vertical field.•Droplet speed increased and its size decreased by increasing the continuous phase flow rate in both field directions. In this study, ferrofluid droplet generation in a co-flowing microchannel is numerically studied in the presence of a uniform magnetic field, exerted parallel or perpendicular to the flow direction. The effects of field direction and parameters like the magnetic Bond number and two-phase flow rate ratio on the droplet breakup formation characteristics are investigated. Depending on the field direction, different responses of the system to alterations in the mentioned parameters are observed. By increasing the magnetic Bond number, droplet dimensionless diameter and dimensionless velocity increases for the parallel magnetic field and decreased by 5.15% and 36.91% for the vertical field, respectively. Implementing the perpendicular field, the droplet formation properties become insensitive to the magnetic Bond number at values more than 4.24 due to the transformation of the flow pattern from dripping to the slug flow regime. By increasing the two-phase flow rate ratio, the dimensionless diameter of the droplets decreases while their dimensionless velocity increases.