Fall and breakup of miscible magnetic fluid drops in a Hele–Shaw cell

The fall and breakup of a miscible drop of magnetic fluid in a vertical Hele–Shaw cell, taking into account the dependence of the physical properties of the fluid (density, viscosity, diffusion coefficient, and magnetization) on the volume concentration of magnetic particles is studied in the paper numerically and experimentally. There are four governing dimensionless parameters: the Archimedes number Ar, the magnetic Archimedes number Arm, the relative width of the gap between the cell walls δ, and the dimensionless initial half-width of the diffusion front w. As a result of numerical simulation, five types of droplets fall and breakup were found: single drop, pair decay, trident, symmetric breakup, and cascade breakup. In the experiment performed, the correspondence to the data of the numerical analysis is confirmed in the absence of a magnetic field and in the vertical magnetic field.